THE  UNIVERSITY 

OF  ILLINOIS 

LIBRARY 


NATURAL  HISTORY  SURVEY 


5705 
ILL 

v3cop.4 


fU,  <o 

lis) 
I 

V.  3' 


ILLINOIS  BIOLOGICAL 
MONOGRAPHS 

Vol.  Ill  August,  1916  No.  1 


STUDIKSON  THE  FACTORS 

CONTROLLING  THE  RATE  OF 

REGENERATION 


CHARLES  /} 


PRICE      $1.26 


NOIS 


UNIVERSITY  OF  ILLINOIS  STUDIES  PUBLISHED 

ILLINOIS  BIOLOGICAL  MONOGRAPHS 
The  Illinois  Biological  Monographs  is  a  serial  published  quarterly  by  the 
University  of  Illinois.  It  is  the  purpose  of  the  publication  to  present  in  mono- 
graphic form  research  contributions  of  especial  merit  and  of  somewhat  extended 
character.  Each  volume  will  include  about  500  pages  and  20  or  more  full  page 
plates.  The  series  may  be  obtained  under  a  subscription  price  of  three  dollars 
yearly.  Individual  numbers  will  be  sold  separately  at  prices  determined  by  the 
size  and  amount  of  illustration  contained  in  a  particular  number. 

Vol.  I 
:  and  2.    A  revision  of  the  Cestode  family  Proteocephalidae.     With  16  plates. 

By  G.  R.  La  Rue.     ?2.oo. 
No.  3.     Studies  on  the  Cestode  family  Anoplocephalidae.     With   6  plates.     By  H. 

Douthitt.     80  cts. 
No.  4.    Larval  Trematodes  from  North  American  fresh-water  snails.    With  8  plates. 

By  W.  W.  Cort.     $1.20. 

Vol.  II 
No.  1.    The   classification  of   Lepidopterous   larvae.     With   10  plates.     By.   S.   B. 

Fracker.    $1.50. 
No.  2.     On  the  Osteology  of  some  of  the  Loricati.     With  5  plates.     By  Jol 

Gutberlet.    60  cts. 
No.  3.     Studies  on   Gregarincs,  including  twenty-one   new  species  and  a  synopsis 

of    the    Eugregarine    records    from    the    Myriopoda,    Coleoptera    and 

Orthoptera   of   the  world.     With    15   plates.     By   Minnie   E.   Watson. 

$2.00. 
No.  4.     The  Genus   Meliola   in    Porto   Rico.     With   5   plat  Frank    Lincoln 

Stevens.     75  cts. 

Vol.   Ill 
.     Studies  on  the   factors  controlling  the  rate  of   regeneration.     By  Charles 

leny.     $1.25. 
2.     The  head  capsule  and  mouth-parts  of  Diptera.    With  27  plal  \lvah 

Peterson.  {In  press.) 
UNIVERSITY  OF  ILLINOIS  STUDIES  IN  LANGUAGE  AND  LITERATURE 
The  Studies  in  Language  and  Literature  are  designed  to  include  monographs 
in  general  linguistics  and  comparative  literature;  the  classical  languages  and 
Sanskrit;  the  Romance  languages;  and  English,  the  Scandinavian,  and  other  Ger- 
manic languages.  The  title  of  the  series  will  be  so  construed  as  to  admit  the  publi- 
cation of  such  researches  in  the  history  of  culture  as  may  throw  light  upon  the 
processes  of  language  and  the  interpretation  of  literature.  It  is  a  serial  published 
quarterly,  for  which  the  annual  subscription  price  is  three  dollars. 

Vol.  I 
Nos.  1  and  2.    The  phonology  of  the  dialect  of  Aurland,  Norway.     By  George  T. 

Flom.    $1.25.- 
Nos.  3  and  4.     Studies  in  the  Milton  tradition.     By  John  Walter  Good.     ?i, 

Vol   II 
:    a    biographical   and   critical    study.     By    Clar 
ker.    $1.00. 
Illustrations    of  I    romance    on    tiles    from    CI  •    ,B^ 

er  Sherman  Lo  cts. 

v  Henry  Alfr< 


Entered    a*    second    class    matter    July    27,    1915.    at    tin  under 


a  means  i  jmbers  of 

•logy, 
ption 


P.  C.  Phillip? 

of  print. 

Vol.  Ill 

:c  Scandir.  "ted  States 

arch  and  state 


Reed.    $1.05. 


i     G. 


iigs  before  1846.    By  C.  '  son.    95  ct 

i.e    defer  rentier    policy    of    Augustus. 

I  H.  V.  ( 


act)    and 


Clol 

dex  of  the  XI 

h  an  introduction  treating  c 
Bv  T.  E.  Oliver.     $1.75. 


PUBLICATIONS  OF  THE  UNIVERSITY  OF  ILLINOIS 

Following  is  a  partial  list  of  the  publications  issued  at  the  University : 

j.  iy  of  Illinois  Studies  in  Language  and  Literature.    Pub 

lished  quarterly.     Three   dollars   a   year.     Address    158B   Administration    Building, 

University  of  Illinois. 

2.  The  University  of  Illinois  Studies  in  the  Social  Sciences.  Monographs 
in  history,  economics,  political  science,  and  sociology.  Published  quarterly.  Three 
dollars  a  year.    Address  158B  Administration  Building,  University  of  Illinois. 

3.  The  Illinois  Biological  Monographs.  Published  quarterly.  Three  dollars 
a  year.     Address  158B  Administration  Building,  University  of  Illinois. 

4.  The  University  Studies.  A  series  of  monographs  on  miscellaneous  sub- 
jects. Address  Manager  of  University  Studies,  158B  Administration  Building, 
University  of  Illinois. 

5.  The  Journal  of  English  and  Germanic  Philology.  Published  quarterly. 
Three  dollars  a  year.  Address  Manager  of  Journal  of  English  and  Germanic 
Philology,   158B  Administration  Building,  University  of  Illinois. 

6.  The  Bulletin  of  the  Engineering  Experiment  Station.  Reports  of  the 
research  work  in  the  Engineering  Experiment  Station.  Address  Director  of  Engi- 
neering Experiment  Station,  University  of  Illinois. 

7.  The  Bulletin  of  the  Agricultural  Experiment  Station.  Address  Di- 
rector of  Agricultural  Experiment  Station,  University  of  Illinois. 

8.  The  Bulletin  of  the  State  Laboratory  of  Natural  History.  Address 
Director  of  State  Laboratory  of  Natural  History,  University  of  Illinois. 

9.  The  Bulletin  of  the  State  Geological  Survey.  Address  Director  of 
State  Geological  Survey,  University  of  Illinois. 

10.  The  Bulletin  of  the  State  Water  Survey.  Address  Director  of  State 
Water  Survey,  University  of  Illinois. 

11.  The  Report  of  the  State  Entomologist.  Address  State  Entomologist, 
University  of  Illinois. 

12.  The  Bulletin  of  the  Illinois  Association  of  Teachers  of  English. 
Address  301  University  Hall,  University  of  Illinois. 

13.  The  Bulletin  of  the  School  of  Education.  Address  203  University  Hall, 
University  of  Illinois. 

14.  The  general  series,  containing  the  University  catalog  and  circulars  of 
special  departments.    Address  The  Registrar,  University  of  Illinois. 


ILLINOIS  BIOLOGICAL 
MONOGRAPHS 


PUBLISHED  QUARTERLY 

UNDER  THE  AUSPICES  OF  THE  GRADUATE  SCHOOL 

BY  THE  UNIVERSITY  OF  ILLINOIS 


VOLUME  III 


Urbana,  Illinois 
1916-1917 


Editorial  Committee 


Stephen  Alfred  Forbes      .  William  Trelease 

Henry  Baldwin  Ward 


S70.S 


C^0 


rr 


TABLE  OF  CONTENTS 

Volume  III 

NUMBERS  PAGES 

i        Studies  on  the  Factors  Controlling  the  Rate  of  Regeneration. 

By  Charles  Zeleny  1-170 

(Distributed  November  29,  1916) 

2        The  Head-Capsule  and  Mouth-Parts  of  Diptera.     By  Alvah 

Peterson.     With   25   plates 171-284 

(Distributed  December  30,  1916) 


3  Studies  on  North  American  Polystomidae,  Aspidogastridae,  and 
Paramphistomidae.  By  Horace  Wesley  Stunkard.  With 
11    plates  285-394 

(Distributed  May  5.  1917) 


4        Color  and  Color-Pattern  Mechanism  of  Tiger  Beetles.     By  Victor 

E.  Shelford.     With  29  black  and  3  colored  plates 395-532 

(Distributed  June  30,  1917) 


ILLINOIS  BIOLOGICAL 
MONOGRAPHS 


Vol.  Ill  August,  1916  No.  1 


Editorial  Committee 


Stephen  Alfred  Forbes  William  Trelease 

Henry  Baldwin  Ward 


Published  under  the 

Auspices  of  the  Graduate  School  by 

the  University  of  Illinois 


Copyright,  1915 
By  the  University  of  Illinois 
Distributed  November  29,  1916 


STUDIES  ON  THE   FACTORS 

CONTROLLING  THE  RATE  OF 

REGENERATION 


BY 


CHARLES  ZELENY 


Contributions   from   the 
Zoological  Laboratory  of  the  University  of  Illinois,  No.  73 


732172 


TABLE  OF  CONTENTS 


PAGE 

Introduction    7 

The  Rate  of  Regeneration  from  New  Tissue  Compared  with  That  from  Old 

Tissue    9 

The  Effect  of  Successive  Removal  upon  the  Rate  and  Completeness  of  Regen- 
eration   / 26 

The  Effect  of  Level  of  the  Cut  upon  the  Rate  and  Completeness  of  Regeneration  61 

The  Change  in  Rate  of  Regeneration  during  the  Regenerative  Process 108 

The  Effect  of  Degree  of  Injury  upon  the  Rate  of  Regeneration 136 

The  Completeness  of  Regeneration 158 

Bibliography 167 


7]  RATE    OF    REGENERATION— ZELENY 


INTRODUCTION. 

The  present  studies  of  the  factors  controlling  rate  of  regeneration 
are  a  continuation  of  previous  work  on  the  subject.  An  advance  in 
knowledge  concerning  certain  of  the  factors  has  made  possible  an  exten- 
sion of  the  experimental  analysis  of  others.  The  present  studies  are 
therefore  closely  related.  In  fact  in  several  cases  a  single  series  of  indi- 
viduals has  been  of  value  in  connection  with  more  than  a  single  factor. 
The  definite  determinations  of  the  effect  of  level  of  the  cut  and  of  the 
change  in  rate  during  the  regeneration  cycle  have  been  of  particular 
value. 

The  precautions  taken  to  meet  the  demands  of  the  experiments  are 
not  discussed  in  detail  because  they  have  already  been  given  in  previous 
papers.  The  frog  tadpoles  (when  they  can  be  used)  are  in  all  respects 
more  suitable  than  salamander  larvae.  When  collected  late  in  the  fall 
they  can  be  kept  at  a  fairly  constant  size  and  the  results  obtained  under 
these  conditions  are  not  complicated  with  growth  phenomena.  They 
have  proved  to  be  remarkably  uniform  in  several  series.  The  salamander 
larvae  on  the  other  hand  vary  in  rate  of  regeneration  from  day  to  day. 
The  factors  involved  in  this  fluctuation  were  not  discovered  and  could 
not  be  remedied  but  may  be  related  in  some  way  to  the  fact  that  these 
animals  require  living  active  food  and  the  feeding  reactions  are  therefore 
more  complicated  than  in  frog  tadpoles  and  more  subject  to  disturbance. 

In  regard  to  certain  factors,  such  as  the  degree  of  injury,  in  which 
expected  differences  in  rate  are  slight  the  writer  has  felt  that  he  might 
be  biased  in  making  the  measurements  and  in  a  number  of  cases  this 
work  was  therefore  delegated  to  a  person  who  had  no  preconceptions 
concerning  the  result. 

In  making  averages  elimination  of  individual  cases  is  avoided 
except  for  a  few  very  aberrant  values.  Such  exceptional  values  are  in 
every  case  however  included  in  the  tables.  In  many  cases  where  only 
slight  differences  are  to  be  expected  several  different  kinds  of  comparisons 
are  made  so  as  to  bring  out  the  correct  relation  as  completely  as  possible. 

As  in  the  past  all  data  obtained  by  the  writer  on  the  particular 
factors  in  question  are  given.  The  practice  of  selective  elimination  would 
be  dangerous  because  of  the  large  value  of  factors  not  at  present  under 
experimental  control. 


8  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [8 

Discussions  of  the  results  of  other  workers  are  included  in  the  pre- 
vious papers  and  need  not  be  repeated  here.  The  principal  need  at 
present  seems  to  be  an  extension  of  knowledge  of  these  factors  by 
multiplying  the  number  of  series  of  carefully  controlled  experiments. 
While  it  would  be  interesting  to  know  why  a  particular  series  differs 
from  others  with  respect  to  a  certain  factor  it  is  not  always  possible  to 
discuss  the  matter  profitably  in  the  absence  of  evidence  as  to  all  the 
factors  concerned. 

Particular  emphasis  must  be  laid  on  the  fact  that  in  connection  with 
some  at  least  of  the  factors  it  has  been  possible  to  make  out  very  definite 
quantitative  relations.  These  have  been  checked  up  in  a  number  of  cases 
by  agreement  between  separate  series  of  experiments.  The  success  in  this 
direction  has  made  it  very  probable  that  with  a  more  accurate  control 
of  external  conditions  there  will  be  a  considerable  further  advance  in 
our  knowledge  of  the  factors  controlling  rate  of  regeneration. 


9]  RATE    OF    REGENERATION— ZELENY 


PARTI 

THE  EATE  OF  REGENERATION  FROM  NEW  TISSUE  COM- 
PARED WITH  THAT  FROM  OLD  TISSUE 

In  comparing  first  and  second  regenerations  from  the  same  level 
one  of  the  difficulties  that  presents  itself  is  the  impossibility  of  making 
the  second  cut  exactly  in  the  path  of  the  first.  This  is  true  not  only 
because  of  the  error  in  manipulation  but  also  because  the  old  and  the 
new  tissues  become  intermingled  and  do  not  retain  a  distinct  dividing 
line.  At  the  cut  surface  there  is  old  tissue  alone,  old  and  new  tissue, 
or  new  tissue  alone  according  as  the  second  cut  comes  inside  of  the  first 
level,  exactly  at  the  level,  or  outside  of  it. 

The  experiments  about  to  be  described  were  devised  with  a  view  to 
the  testing  of  the  relative  rates  from  old  and  from  new  tissue.  Other 
factors  being  eliminated,  are  new  cells  which  are  recently  produced  in 
a  regenerating  part  able  to  carry  on  a  repetition  of  the  process  more 
expeditiously  than  old  cells  which  have  not  been  directly  concerned  in 
such  a  process? 

There  has  been  no  selective  elimination  of  data.  As  in  former 
papers  of  a  similar  character  all  the  data  obtained  by  the  author  on  the 
topic  at  hand  are  included. 

Experiment  I      Series  3628-3675 

Tadpoles  of  Rana  clamitans  with  an  average  length  of  33.4 
mm.  were  used.  They  were  fed  just  enough  to  keep  them  in  good 
condition  without  much  growth.  All  were  collected  at  one  time  in  a 
single  pool  and  during  the  course  of  the  experiment  factors  apart  from 
the  one  under  investigation  were  made  as  nearly  alike  as  possible.  This 
elimination  of  outside  factors  was  facilitated  by  subdividing  the  tad- 
poles into  sets  of  two  each,  the  two  individuals  of  a  set  being  exactly 
alike  except  for  the  factor  under  consideration  and  one  being  used  for 
regeneration  from  old  tissue  and  the  other  for  regeneration  from  new 
tissue. 


10 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[10 


Within  each  set  the  tail  of  tadpole  1  was  removed  at  B  (Fig.  1) 
and  the  tail  of  tadpole  2  at  A.  The  distance  between  A  and  B  was  2 
or  3  mm.  After  21  days  of  regeneration  the  second  operation  on 
both  tadpoles  came  between  A  and  B  and  therefore  in  old  tissue  in 
tadpole  1  and  in  new  tissue  in  tadpole  2.     This  procedure,  insuring 


X      B 


Figure  1.  Outline  of  tadpole  of  Rana  clamitans-  Individuals  used  for  re- 
generation from  old  tissue  have  the  original  removal  level  at  B  and  the  second 
level  at  A.  Individuals  used  for  regeneration  from  new  tissue  have  the  original 
removal  level  at  A  and  the  second  level  at  B.  Regenerations  from  the  second 
levels  are  compared. 

approximately  the  same  level  in  the  two  cases,  is  necessary  because  level 
of  the  cut  has  a  great  influence  upon  rate  of  regeneration.  Eleven  pairs 
of  individuals  weue  used  in  the  comparison.  The  precautions  taken  to 
eliminate  possible  error  are  treated  fully  elsewhere  for  similar  cases 
(Zeleny  1909a,  1909b). 

The  data  are  given  in  Table  1.  The  removed  tail  lengths  are  the 
lengths  of  the  original  removed  portions  of  the  tail  plus  or  minus  the 


EXPLANATION  OF  TABLE  I. 

Note  1.  The  removed  length  is  the  length  of  the  original  removed  portion 
of  the  tail  plus  or  minus  the  distance  of  the  new  cut  surface  from  the  dividing 
line  between  the  old  and  new  tissue. 

Note  2.  The  lengths  as  given  are  the  living  lengths.  Measurements  were 
made  on  material  killed  in  Gilson's  mercuro-nitric  mixture  and  preserved  in 
85%  alcohol.  Sets  I  and  IX  were  measured  both  when  alive  and  after  killing 
and  preserving.  From  tljem  the  shrinkage  coefficient  was  obtained  and  this 
made  possible  the  reduction  of  all  the  data  to  the  living  basis. 

Note  3.  The  specific  amount  regenerated  in  any  case  is  the  amount  regen- 
erated per  unit  of  removed  length. 

Note  4.  The  average  includes  only  the  sets  in  which  both  individuals  are 
present. 


11] 


RATE    OF    REGENERATION —ZELENY 


11 


TABLE  I. 

Series  3628-3675 


Old  or  New 
tissue 
at  cut 
surface 

Cata- 
log 
number 

Total 

length 

mm. 

Tail 
length 
mm. 

Re- 
moved 
length 

mm. 

Regeneration 
Time  6  days 

Regen-  1  Specific 
erated      length 
length      reg«n- 
mm.     1  erated 

Regeneration 
Time  8  days 

Set 

Regen-     I  Specific 

erated     |    length 

length     I    regen- 

min.       I  erated 

I 

old 

new 

3628 
3629. 

38.0 
39.2 

24.1 
24.6 

13.2 
12.8 

2.2 
2.3 

0.17 
0.18 

3.5 
3.1 

0.27 
0.24 

II 

old 
new 

3633 
3632 

35.7 
33.8 

23.2 
22.1 

12.3 
10.2 

2.0 
1.8 

0.16 
0.18 

3.4 

0.28 

III 

old 
new 

3636 
3637 

35.8 
38.4 

~32T9~ 
31.4 

23.1 
25.0 

12.8 
11.9 

2.0 
2.4 

0.16 
0.20 

3.25 
3.5 

0.25 
0.29 

IV 

old 
new 

3641 
3640 

20.8 
20.4 

11.3 
9.3 

1.7 

2.2 

0.15 
0.24 

3.4 

0.30 

V 

old 
new 

3645 
3644 

37.5 
42.8 

23.8 
29.2 

11.5 
15.1 

2.2 
2.3 

0.19 
0.15 

0.21  ~~ 
0.21 

— 



VI 

old 
new 

3649 
3648 

37.0 
35.9 

25.6 
23.3 

11.2 
9.9 

9.2 

2.3 
2.1 

3.1 
3.1 

0.28 
0.31 

VII 

old 
new 

3652 
3653 

31.3 
29.0 

20.8 
19.2 

2.4 

0.26 

3.6 

0.39 

VIII 

old 

»         new 

3656 
3657 

31.8 
33.0 

21.1 
22.0 

13.2 
11.7 

2.4 

2.7 

0.18 
0.23 

4.9 

0.42 

IX 

old 

new 

3660 
3661 

26.5 
29.4 

17.0 
19.0 

9.6 

8.7 

2.5 

2.0 

0.26 
0.23 

0.17 
0.20 

3.5 
3.0 

0.36 
0.34 

X 

old 

new 

3668 
3669 

31.1 
32.4 

20.8 
21.8 

9.2 
8.9 

1.6 

1.8 

2.3 

2.5 

0.25 
0.28 

XI 

old 
new 

3672 
3673 

24.4 
28.5 

15.8 
18.1 

8.6 
8.7 

2.7 
1.9 

0.31 
0.22 

3.5 
3.5 

0.41 
0.40 

Average  of  old 
Average  of  new 

32.9 
34.0 

21.5 
22.2 

11.3 
10.7 

2.16 
2.15 

0.196 
0.204 

3.19 
3.12 

0.303 
0.310 

Old — ahead 
New — ahead 

0.01 

0.008 

0.07 

0.007 

Old — Times  ahead 
New — Times  ahead 

4 
6 

3!/2 
«S4 

3 
3 

3 
3 

12  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [12 

distances  of  the  new  cut  surface  from  the  dividing  line  between  the  old 
and  the  new  tissue.  The  regenerated  lengths  as  given  are  the  living 
lengths.  Measurements  were  made  on  material  killed  in  Gilson's  mer- 
curo-nitric  fluid  and  preserved  in  85%  alcohol.  Sets  I  and  IX  were 
measured  both  when  alive  and  after  killing  and  preserving.  From  them 
the  shrinkage  coefficient  was  obtained  and  this  made  possible  the  reduc- 
tion of  all  the  data  to  the  living  basis.  The  averages  include  only  the 
sets  in  which  both  individuals  are  present.  The  specific  amount  of 
regeneration  is  the  amount  regenerated  per  unit  of  removed  length.  It 
has  been  shown  that  within  wide  limits  this  is  a  constant  if  the  only 
variable  in  the  experiment  is  the  amount  removed.  This  statement  holds 
for  all  levels  in  the  present  experiment. 

The  table  shows  that  the  average  amount  regenerated  at  the  end 
of  six  days  is  2.16  mm.  from  the  old  tissue  levels  and  2.15  mm. 
from  the  new  tissue  levels.  The  new  tissue  levels  however  rep- 
resent the  shorter  amount  removed,  10.7  mm.  as  opposed  to  11.3 
for  the  old  tissue  levels.  This  gives  an  average  specific  rate  of  0.204 
for  the  new  levels  and  0.196  for  the  old  levels.  The  difference  is  proba- 
bly not  significant.  The  individual  specific  amounts  in  pairs,  putting 
the  old  tissue  first  and  the  new  tissue  second  in  each  case,  are  0.17  and 
0.18,  0.16  and  0.18,  0.16  and  0.20,  0.15  and  0.24,  0.19  and  0.15,  0.21 
and  0.21,  0.18  and  0.23,  0.26  and  0.23,  0.17  and  0.20,  and  0.31  and  0.22. 
The  old  tissue  is  ahead  three  times,  the  new  six  times  and  there  is  a  tie 
in  one  case. 

At  the  end  of  eight  days  the  result  is  similar.  There  is  a  slight 
advantage  in  favor  of  the  new  tissue  level  but  this  cannot  be  considered 
as  significant.  The  average  amount  regenerated  is  3.19  mm.  from  old 
tissue  levels  and  3.12  mm.  from  new  tissue  levels.  The  specific 
amount  regenerated  is  0.303  for  the  old  and  0.310  for  the  new  level. 
The  individual  amounts  by  pairs  putting  the  old  tissue  level  first  as 
before  are  0.27  and  0.24,  0.25  and  0.29,  0.28  and  0.31,  0.36  and  0.34, 
0.25  and  0.28,  and  0.41  and  0.40.  Each  level  is  ahead  of  the  other  in 
three  of  the  six  cases. 

Experiment  II      Series  3676-3765 

Tadpoles  of  Rana  clamitans  with  an  average  length  of  forty 
mm.  were  used.  The  experiment  was  designed  for  a  study  of  the 
effect  of  successive  removal  on  the  rate  of  regeneration  but  incidentally 
furnishes  valuable  data  for  the  present  problem.  In  removing  the  re- 
generated portion,  the  cut  in  most  cases  did  not  come  exactly  at  the 
border.  In  some  cases  it  was  too  near  the  base  of  the  tail  and  therefore 
the  cells  at  the  cut  surface  were  old  unregenerated  cells.    In  other  cases 


13]  RATE    OF    REGENERATION— ZELENY  13 

it  was  too  near  the  tip  of  the  tail  and  the  cells  at  the  cut  surface  were 
newly  regenerated  ones. 

The  operations  were  at  different  levels  in  different  individuals  but 
the  determination  of  the  specific  amounts  of  regeneration  according  to 
the  method  given  in  the  explanation  of  Experiment  I  eliminates  these 
differences  within  wide  limits.  It  does  not  hold  when  the  level  of  the 
cut  is  very  near  the  tip  or  near  the  base  of  the  tail.  In  the  present 
experiment  the  specific  amount  is  a  fair  constant  for  all  removed 
lengths  of  over  4  mm.  The  individuals  with  a  removed  length  of 
less  than  4  mm.  are  therefore  treated  separately.  Likewise  it  does 
not  hold  for  the  first  few  days  of  regeneration  during  which  regenera- 
tion is  confined  to  active  migration  of  cells  over  the  cut  surface  without 
any  new  formation  by  cell  division.  Separate  comparisons  are  made  at 
4,  6,  8,  10,  12y2,  18  and  56  days  of  regeneration.  The  data  are  given 
in  Tables  2  to  17. 

Taking  first  the  cases  with  a  removed  length  of  over  4  mm.  there 
is  at  four  days  a  specific  amount  of  0.043  for  old  tissue  and  of 
0.045  for  new  tissue.  At  six  days  the  amounts  are  respectively  0.135 
and  0.143,  at  eight  days  0.216  and  0.224,  at  ten  days  0.292  and  0.293, 
at  twelve  and  a  half  days  0.331  and  0.337,  at  eighteen  days  0.352  and 
0.348,  and  at  fifty-six  days  0.345  and  0.346.  The  two  are  approximately 
equal  though  in  six  out  of  the  seven  cases  the  new  tissue  is  ahead.  The 
average  difference  in  favor  of  the  new  tissue  is  0.003. 

For  removed  amounts  of  less  than  4  mm.  the  data  are  un- 
satisfactory because  there  are  only  three  individuals  with  regeneration 
from  new  tissues.  The  data  are  however  of  value  in  comparison  with 
the  others.  The  specific  amounts  at  the  different  days,  again  putting 
the  old  tissue  first  in  each  case,  are  0.119  and  0.160  for  four  days,  0.317 
and  0.327  for  six  days,  0.444  and  0.467  for  eight  days,  0.506  and  0.520 
for  ten  days,  0.517  and  0.517  for  twelve  and  a  half  days,  0.501  and  0.507 
for  eighteen  days,  and  0.475  and  0.325  for  fifty-six  days.  In  the  last 
the  absorption  of  the  tail  had  begun  before  the  measurement  was  made 
and  the  comparison  is  therefore  not  valid  for  our  purposes.  In  the 
first,  0.119  for  old  and  0.160  for  new  at  four  days,  the  great  difference 
between  individual  cases  on  each  side  makes  a  comparison  of  doubtful 
validity.  There  are  other  data  however  which  make  it  probable  that  the 
initial  migration  of  the  cells  takes  place  more  rapidly  from  new  than 
from  old  tissue.  For  the  other  levels  there  is  on  the  average  a  slight 
difference  (0.011)  in  favor  of  the  regeneration  from  new  tissue.  With  but 
a  single  exception,  which  is  a  tie,  the  new  tissue  is  ahead  of  the  old. 
The  differences  favoring  the  new  tissue  are  greater  than  those  for  the 
larger  removals.    This  again  may  be  due  to  the  fact  that  a  larger  percent- 


14 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[14 


age  of  the  regenerated  material  is  derived  from  the  old  by  migration  and 
a  smaller  percentage  by  cell  division.  The  data  unfortunately  are  based 
on  such  a  small  number  of  individuals,  especially  in  the  case  of  new  tissue 
levels,  that  too  much  stress  should  not  be  laid  on  the  differences. 


TABLE  2 
Series  3676-3765       Over  4  millimeters  removed      Regeneration:  4  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regener- 
ated 
mm. 

Specific 
length 
regener- 
ated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regener- 
ated 
mm. 

Specific 
length 
regener- 
ated 

3720 

4.7 

0.42 

0.09 

3756 

4.8 

0.36 

0.07 

3684 

5.5 

0.15 

0.03 

3751 

6.7 

0.45 

0.07 

3715 

7.9 

0.24 

0.03 

3697 

7.3 

0.48 

0.07 

3757 

8.0 

0.42 

0.05 

3721 

8.5 

0.57 

0.07 

3694 

8.7 

0.45 

0.05 

3733 

8.5 

0.36 

0.04 

3685 

9.3 

0.60 

0.06 

3734 

8.5 

0.48 

0.06 

3686 

14.5 

0.60 

0.04 

3739 

9.4 

0.36 

0.04 

3753 

16.8 

0.42 

0.03 

3722 

12.5 

0.60 

0.05 

3723 

18.4 

0.30 

0.02 

3716 

12.7 

0.39 

0.03 

3699 

21.0  i 

0.54 

0.03 

3698 

12.9 

0.50 

0.04 

3759 

15.5 

0.30 

0.02 

3705 

17.6 

0.72 

0.04 

3717 

17.6 

0.42 

0.02 

3687 

19.7 

0.54 

0.03 

Average 

0.043 

Average 

0.045 

Note  1.  No.  3734  is  left  out  in  making  up  the  averages  because  its  specific 
amount  from  six  days  of  regeneration  on  is  very  much  in  excess  of  that  of 
any  of  the  others.  A  probable  explanation  is  that  the  end  of  the  tail  in  this  indi- 
vidual had  been  removed  and  regeneration  had  just  started  when  the  present 
operations  were  begun.  If  this  is  true  it  belongs  to  a  longer  removed  length 
than  indicated  and  the  specific  rate  is  wrong.  Besides  a  highly  exceptional 
individual  even  if  not  explained  should  be  left  out  in  determining  the  average 
value. 


15]  RATE    OF   REGENERATION— ZELENY  15 

TABLE  3 
Series  3676-3765      Over  4  millimeters  removed      Regeneration:  6  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3720 

4.7 

0.84 

"0.18 

3756 

4.8 

1.0 

0.21 

3648 

5.5 

0.7 

0.13 

3751 

6.7 

1.1 

0.16 

3715 

7.9 

0.9 

0.11 

3697 

7.3 

1.2 

0.16 

3757 

8.0 

1.2 

0.15 

3721 

8.5 

1.3 

0.15 

3694 

8.7 

1.5 

0.17 

3733 

8.5 

1.0 

0.12 

3685 

9.3 

1.2 

0.13 

3734 

8.5 

2.1 

0.25 

3686 

14.5 

2.1 

0.14 

3739 

9.4 

1.0 

0.11 

3753 

16.8 

2.0 

0.12 

3722 

12.5 

1.6 

0.13 

3723 

18.4 

2.3 

0.12 

3716 

12.7 

1.7 

0.13 

3699 

21.0 

2.2 

0.10 

3698 

12.9 

1.5 

0.12 

3759 

15.5 

2.0 

0.13 

3705 

17.6 

2.0 

0.11 

3717 

17.6 

2.6 

0.15 

3687 

19.7 

2.6 

0.18 

Average 

0.135 

Average 

0.143 

Series  3676-3765 


TABLE  4 
Over  4  millimeters  removed 


Regeneration:  8  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3720 

4.7 

1.1 

0.23 

3756 

4.8 

1.3 

0.27 

3684 

•  5.5 

1.2 

0.22 

3751 

6.7 

1.7 

0.25 

3715 

7.9 

1.7 

0.22 

3697 

7.3 

1.7 

0.23 

3757 

8.0 

2.1 

0.26 

3721 

8.5 

1.9 

0.22 

3694 

8.7 

2.2 

0.25 

3733 

8.5 

1.9 

0.22 

3685 

9.3 

1.9 

0.20 

3734 

8.5 

3.1 

0.36 

3686 

14.5 

3.4 

0.23 

3739 

9.4 

1.8 

0.19 

3753 

16.8 

2.5 

0.15 

3722 

12.5 

2.6 

0.21 

3723 

18.4 

3.7 

0.20 

3716 

12.7 

2.4 

0.19 

3699 

21.0 

4.3 

0.20 

3698 

12.9 

3.3 

0.26 

3759 

15.5 

3.0 

0.19 

3705 

17.6 

3.6 

0.20 

3717 

17.6 

3.6 

0.20 

3687 

19.7 

5.6 

0.28 

Average 

0.216 

Average 

0.224 

16 


ILLIXOIS    BIOLOGICAL    MONOGRAPHS 


[16 


Series  3676-3765 


TABLE  5 
Over  4  millimeters  removed 


Regeneration:  10  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3720 

4.7 

1.3 

0.28 

3756 

4.8 

1.7 

0.35 

3684 

5.5 

1.4 

0.25 

3751 

6.7 

2.1 

0.31 

3715 

7.9 

2.3 

0.29 

3697 

7.3 

2.2 

0.30 

3757 

8.0 

2.8 

0.35 

3721 

8.5 

2.3 

0.27 

3694 

8.7 

3.2 

0.37 

3733 

8.5 

2.4 

0.28 

3685 

9.3 

2.3 

0.25 

3734 

8.5 

4.5 

0.53 

3686 

14.5 

4.8 

0.33 

3739 

9.4 

2.4 

0.26 

3753 

16.8 

3.8 

0.23 

3722 

12.5 

3.6 

0.29 

3723 

18.4 

5.3 

0.29 

3716 

12.7 

3.4 

0.27 

3699 

21.0 

5.9 

0.28 

3698 

12.9 

4.3 

0.33 

3759 

15.5 

4.2 

0.27 

3705 

17.6 

4.8 

0.28 

3717 

17.6 

5.2 

0.30 

3687 

19.7 

6.0 

0.30 

Average 

0.292 

Average 

0.293 

Series  3676-3765 


TABLE  6 
Over  4  millimeters  removed      Regeneration:  12-13  days 


Old  tissue 


Catalog 
number 


3720 
3684 
3715 
3757 
3694 
3685 
3686 
3753 
3723 
3699 


Average 


Length 

Length 

removed 

regen- 

mm. 

erated 

mm. 

4.7 

1.3 

5.5 

1.4 

7.9 

2.6 

8.0 

3.1 

8.7 

3.4 

9.3 

2.8 

14.5 

5.3 

16.8 

5.2 

18.4 

6.5 

21.0 

7.1 

Specific 
length 
regen- 
erated 


0.28 
0.25 
0.33 
0.39 
0.39 
0.30 
0.37 
0.31 
0.35 
0.34 


New  tissue 


Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3756 

4.8 

1.8 

0.37 

3751 

6.7 

2.4 

0.36 

3697 

7.3 

2.4 

0.33 

3721 

8.5 

2.6 

0.31 

3733 

8.5 

2.6 

0.31 

3734 

8.5 

5.7 

0.67 

3739 

9.4 

3.0 

0.32 

3722 

12.5 

3.9 

0.31 

3716 

12.7 

4.2 

0.33 

3698 

12.9 

5.0 

0.39 

3759 

15.5 

4.8 

0.31 

3705 

17.6 

6.4 

0.36 

3717 

17.6 

6.0 

0.34 

3687 

19.7 

6.6 

0.34 

Average 

0.337 

17] 


RATE    OF    REGENERATION— ZELENY 


17 


Series  3676-3765      Over  4 


TABLE  7 
millimeters  removed 


Regeneration:    17-18-19  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3720 

4.7 

1.3 

0.28 

3756 

4.8 

1.6 

0.33 

3684 

5.5 

1.5 

0.27 

3751 

6.7 

2.5 

0.37 

3715 

7.9 

2.6 

0.33 

3697 

7.3 

2.3 

0.32 

3757 

8.0 

3.2 

0.40 

3721 

8.5 

2.3 

0.27 

3694 

8.7 

3.4 

0.39 

3733 

8.5 

2.6 

0.31 

3685 

9.3 

3.0 

0.32 

3734 

8.5 

6.4 

0.75 

3686 

14.5 

5.2 

0.36 

3739 

9.4 

2.9 

0.31 

3753 

16.8 

6.4 

0.38 

3722 

12.5 

3.5 

0.28 

3723 

18.4 

8.1 

0.43 

3716 

12.7 

5.1 

0.40 

3699 

21.0 

7.5 

0.36 

3698 

12.9 

5.4 

0.42 

3759 

15.5 

6.7 

0.43 

3705 

17.6 

6.2 

0.35 

3717 

17.6 

6.7 

0.38 

3687 
Average 

19.7 

7.0 

0.36 

Average 

0.352 

0.348 

Series  3676-3765 


TABLE  8 
Over  4  millimeters  removed 


Regeneration:    55-56-57  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3720 

4.7 

1.3 

0.28 

3756 

4.8 

— 



3684 

5.5 

1.4 

0.25 

3751 

6.7 

2.3 

0.34 

3715 

7.9 

2.8 

0.35 

3697 

7.3 

2.1 

0.29 

3757 

8.0 

3.1 

0.39 

3721 

8.5 

2.2 

0.26 

3694 

8.7 

— 



3733 

8.5 

2.8 

0.33 

3685 

9.3 

2.6 

0.28 

3734 

8.5 

6.6 

0.78 

3686 

14.5 

— 



3739 

9.4 

— 



3753 

16.8 

7.1 

0.42 

3722 

12.5 

4.2 

0.34 

3723 

18.4 

8.3 

0.45 

3716 

12.7 

4.4 

0.35 

3699 

21.0 

7.2 

0.34 

3698 

12.9 

5.4 

0.42 

3759 

15.5 

6.6 

0.43 

3705 

17.6 

6.0 

0.34 

3717 

17.6 

6.4 

0.36 

3687 

19.7 

— 



Average 

0.345 

Average 

0.346 

18 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[18 


Series  3676-3765 


TABLE  9 
Over  4  millimeters   removed 


Summary  Tables  2  to  8 


Table 
number 


Average 


Days  of 
regeneration 


10 


12,13 


17,18,19 


55,  56,  57 


Old   tissue 

Specific 

length   of 

regeneration 


0.043 


0.135 


0.216 


0.292 


0.331 


0.352 


0.345 


New  tissue 

Specific 

length    of 

regeneration 


0.045 

0.143 

0.224 

0.293 

0.337 

0.348 

0.346 


Old 
ahead 


0.004 


New 
ahead 


0.002 


0.008 


0.008 


0.001 

0.006 

0.001 

0.003 

Series  3676-3765 


TABLE  10 
Less  than  4  millimeters  removed      Regeneration:  4  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 

mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 

mm. 

Specific 
length 
regen- 
erated 

3676 

1.3 

0.27 

0.27 

3696 

2.1 

0.48 

0.23 

3682 

1.6 

0.18 

0.11 

3749 

2.8 

0.30 

0.11 

3730 

1.6 

Q.39 

0.24 

3750 

3.5 

0.48 

0.14 

3754 

1.6 

0.06 

0.04 

3718 

2.1 

0.06 

0.03 

3731 

2.7 

0.15 

0.06 

3713 

2.8 

0.36 

0.13 

3719 

3.1 

0.36 

0.12 

3701 

3.2 

0.42 

0.13 

Average 

0.119 

Average 

0.160 

19] 


RATE    OF    REGENERATION— ZELENY 


19 


Series  3676-3765 


TABLE  11 
Less  than  4  millimeters  removed 


Regeneration:  6  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3676 

1.3 

0.6 

0.46 

3696 

2.1 

0.85 

0.40 

3682 

1.6 

0.6 

0.37 

3749 

2.8 

0.6 

0.21 

3730 

1.6 

0.75 

0.47 

3750 

3.5 

1.3 

0.37 

3754 

1.6 

0.55 

0.34 

3718 

2.1 

0.45 

0.21 

3731 

2.7 

0.5 

0.19 

3713 

2.8 

0.8 

0.29 

3719 

3.1 

0.84 

0.27 

3701 

3.2 

0.8 

0.25 

Average 

0.317 

Average 

0.327 

Series  3676-3765 


TABLE  12 
Less  than  4  millimeters  removed 


Regeneration:  8  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3676 

1.3 

0.9 

0.69 

3696 

2.1 

1.0 

0.48 

3682 

1.6 

0.9 

0.56 

3749 

2.8 

1.2 

0.43 

3730 

1.6 

0.9 

0.56 

3750 

3.5 

1.7 

0.49 

3754 

1.6 

0.9 

0.56 

3718 

2.1 

0.7 

0.33 

3731 

2.7 

0.8 

0.29 

3713 

2.8 

0.9 

0.32 

3719 

3.1 

1.1 

0.35 

3701 

3.2 

1.1 

0.34 

Average 

0.444 

Average 

0.467 

20 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[20 


Series  3676-3765 


TABLE  13 
Less  than  4  millimeters  removed 


Regeneration:   10  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3676 

1.3 

0.9 

0.69 

3696 

2.1 

1.1 

0.52 

3682 

1.6 

1.0 

0.62 

3749 

2.8 

1.4 

0.50 

3730 

1.6 

0.9 

0.56 

3750 

3.5 

1.9 

0.54 

3754 

1.6 

1.1 

0.69 

3718 

2.1 

1.0 

0.48 

3731 

2.7 

1.0 

0.37 

3713 

2.8 

0.9 

0.32 

3719 

3.1 

1.4 

0.45 

3701 

3.2 

1.2 

0.37 

Average 

0.506 

Average 

0.520 

Series  3676-3765 


TABLE   14 
Less  than  4  millimeters  removed 


Regeneration:  12-13  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3676 

1.3 

0.9 

0.69 

3696 

2.1 

1.0 

0.48 

3682 

1.6 

1.0 

0.62 

3749 

2.8                1.4 

0.50 

3730 

1.6 

0.9 

0.56 

3750 

3.5 

2.0 

0.57 

3754 

1.6 

1.2 

0.75 

3718 

2.1 

1.0 

0.48 

3731 

2.7 

1.0 

0.37 

3713 

2.8 

0.9 

0.32 

3719 

3.1 

1.4 

0.45 

3701 

3.2 

1.3 

0.41 

Average 

0.517 

Average 

0.517 

21] 


RATE    OF    REGENERATION— ZELENY 


21 


TABLE  15 
Series  3676-3765     Less  than  4  millimeters  removed     Regeneration:  17-18-19  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 
mm. 

Specific 
length 
regen- 
erated 

3676 

1.3 

0.9 

0.69 

3696 

2.1 

1.0 

0.48 

3682 

1.6 

1.0 

0.62 

3749 

2.8 

1.3 

0.47 

3730 

1.6 

0.9 

0.56 

3750 

3.5 

2.0 

0.57 

3754 

1.6 

1.2 

0.75 

3718 

2.1 

0.5 

0.24 

3731 

2.7 

— 



3713 

2.8 

0.9 

0.32 

3719 

3.1 

1.3 

0.42 

3701 

3.2 

1.3 

0.41 

Average 

0.501 

Average 

0.507 

TABLE   16 
Series  3676-3765     Less  than  4  millimeters  removed     Regeneration:  55-56-57  days 


Old  tissue 

New  tissue 

Catalog 
number 

Length 

removed 

mm. 

Length 
regen- 
erated 

mm. 

Specific 
length 
regen- 
erated 

0.54 

Catalog 
number 

Length 
removed 

mm. 

Length 
regen- 
erated 

mm. 

Specific 
length 
regen- 
erated 

3676 

1.3 

0.7 

3696 

2.1 

0.7 

0.33 

3682 

1.6 

1.1 

0.69 

3749 

2.8 

0.9 

0.32 

3730 

1.6 

0.7 

0.44 

3750 

3.5 

— 



3754 

1.6 

1.1 

0.69 

3718 

2.1 

— 



3731 

2.7 

— 



3713 

2.8 

0.5 

0.18 

3719 

3.1 

— 



3701 

3.2 

1.0 

0.31 

Average 

0.475 

Average 

0.325 

22 


ILLIXOIS    BIOLOGICAL    MONOGRAPHS 


[22 


TABLE    17 
Series  3676-3765       Less  than  4  millimeters  removed       Summary  Tables  10  to  16 


Table 
number 

Days  of 
regeneration 

Old   tissue 

Specific 

length    of 

regeneration 

New  tissue 

Specific 

length    of 

regeneration 

Old 
ahead 

New 
ahead 

10 

4 

0.119 

0.160 

0.041 

11 

6 

0.317 

0.327 

0.010 

12 

8 

0.444 

0.467 

0.023 

13 

10 

0.506 

0.520 

0.014 

14 

12,13 

0.517 

0.517 

0.000 

0.000 

15 

17,18,19 

0.501 

0.507 

0.006 

16 

55,  56,  57 

0.475 

0.325 

0.150 

Average 

0.011 

Note  1.  Because  of  the  great  variability  in  the  data  the  average  for  the 
four-day  period  is  not  of  much  value  and  is  therefore  not  included  in  the  grand 
average. 

Note  2.  The  .absorption  of  the  regenerated  portion  of  the  tail  was  pro- 
ceeding so  rapidly  by  the  fifty-fifth  day  of  regeneration  that  this  average 
should  not  be  included  in  the  grand  average. 


Experiment  III       Series  3557-3624 

This  experiment  was  planned  for  a  study  of  the  effect  of  repeated 
removal  and  regeneration  upon  the  rate  of  metamorphosis  but  it  yields 
data  of  value  for  the  present  problem.  Tadpoles  of  Rana  clamitans 
with  an  average  length  of  about  40  mm.  were  used.  In  some  cases 
the  cuts  were  made  inside  of  the  first  level  and  therefore  in  old 
tissue  and  in  other  cases  outside  of  the  first  level  and  therefore  in  new 
tissue. 

The  data  include  third,  fourth  and  fifth  successive  regenerations. 
The  time  of  regeneration  is  37  days  for  the  third  and  36  days  for  the 
fourth  and  for  the  fifth  regenerations.  The  length  of  time  is  more  than 
sufficient  for  the  completion  of  the  process  of  regeneration  in  so  far  as 
it  is  completed.  The  data  therefore  do  not  serve  for  the  rate  but  for 
the  completeness  of  regeneration  from  old  as  compared  with  new  levels. 
Approximately  one-half  of  the  original  tail  length  was  removed  but 
measurements  were  not  made  of  individual  removed  lengths,  so  that 


23] 


RATE    OF    REGENERATION— ZELENY 


23 


specific  rates  of  regeneration  can  not  be  calculated.  However  the  re- 
moved lengths  were  so  nearly  alike  as  to  make  the  regenerated  lengths 
of  value  in  direct  comparison. 

The  data  are  given  in  Table  18.  The  average  length  of  the 
third  regeneration  is  7.9  mm.  for  both  the  old  and  the  new  tissue 
basis.  For  the  fourth  regeneration  the  value  from  old  tissue  is 
5.3  mm.  and  from  new  tissue  5.5  mm.  The  corresponding  values 
for  the  fifth  regeneration  are  6.6  mm.  and  5.9  mm.  Averaging 
the  individual  cases  for  all  three  regenerations  the  old  tissue  average 
is  6.5  mm.  and  the  new  tissue  average  6.6  mm.,  an  advantage  in 
favor  of  the  latter  of  0.1  mm.  This  difference  can  not  be  consid- 
ered as  significant,  especially  since  for  the  individual  regenerations 
the  two  levels  give  equal  regenerated  lengths  for  the  third,  the  new  is 
slightly  ahead  at  the  fourth  and  the  old  is  ahead  at  the  fifth. 

On  the  whole  the  data  for  Experiment  III  agree  with  those  for 
Experiments  I  and  II.  There  is  no  striking  difference  between  com- 
pleteness of  regeneration  from  old  and  from  new  tissue  levels,  though 
a  small  difference  favoring  the  latter  persists  in  practically  all  the 
comparisons. 

TABLE  18 

Rana   clamitans  Series   3557-3624 

Regenerated  tail  length  from  new  tissue  compared  with  that  from  old  tissue 

during  the  third,  fourth  and  fifth  regenerations 


Third 
regeneration 

Fourth 
regeneration 

36  Days 

Fifth 
regeneration 

Third,  fourth  and 

fifth 

regenerations 

combined 

37  Days 

36  Days 

Old 

New 

Old             New 

Old 

New 

Old               New 

tissue 
2.0 

tissue 

tissue         tissue 

tissue 

tissue 

tissue 

tissue 

5.7 

4.4            4.9 

4.7 

5.2 

6.8 

6.6 

4.5            5.4 

5.5 

5.7 

6.9 

8.0 

4.8            5.5 

6.2 

5.9 

7.5 

8.3 

4.9            6.1 

6.5 

6.8 

7.9 

9.3 

5.0 

7.1 

9.0 

9.7 

5.1 

7.2 

9.4 

5.8 
6.1 
7.3 

7.9 
8.0 

Average 

in  mm. 

7.9 

7.9 

5.3            5.5 

6.6 

5.9 

6.5 

6.6 

Difference 

in  mm. 

0.0 

0.0 

+0.2 

+0.7 

+0.1 

24  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [24 

Discussion 

While  the  knowledge  of  the  relative  rates  of  regeneration  for  old 
and  new  tissue  is  essential  for  accurate  determination  of  other  factors 
its  main  interest  is  in  its  bearing  on  the  question  of  the  character  of 
control  of  the  process  of  regeneration.  Evidence  from  a  great  many- 
directions  points  toward  the  conclusion  that  regeneration  is  not  wholly 
a  direct  response  of  the  injured  cells  at  the  cut  surface  nor  of  those  in 
the  immediate  neighborhood  of  the  cut  surface.  It  is  more  and  more 
evident  that  conditions  in  parts  of  the  body  remote  from  the  injured 
region  are  involved.  If  rate  of  regeneration  were  determined  wholly 
by  the  character  of  the  cells  at  the  cut  surface  we  would  expect  that 
cells  in  process  of  active  proliferation,  such  as  thoijie  that  are  starting 
to  build  up  a  new  tail,  would  respond  much  more  promptly  than  those 
which  have  become  more  highly  differentiated  and  hence  more  stable. 
Regenerating  cells  ought  to  furnish  a  much  better  basis  than  old  ones. 
We  find  however  that  there  is  no  striking  difference  in  the  two  cases. 
Regeneration  proceeds  at  approximately  the  same  rate  whether  old  or 
new  cells  have  furnished  the  basis  for  the  new  material.  It  is  true  that 
the  data  show  on  the  average  a  slight  advantage  in  favor  of  the  new 
tissue,  especially  during  the  early  periods,  but  this  advantage  is  small 
and  it  is  doubtful  whether  it  can  be  considered  as  significant.  There  is 
some  evidence  that  the  earliest  stages  of  regeneration,  those  due  to  cell 
migration  exclusively,  are  more  rapid  from  new  than  from  old  tissue. 
If  this  evidence  is  reliable  an  explanation  is  found  for  the  slight  advan- 
tage in  favor  of  the  new  tissue  at  later  periods. 

Summary 

1.  A  comparison  of  the  rate  of  regeneration  in  tadpoles  of  Rana 
clamitans  in  cases  where  there  are  newly  regenerated  cells  at  the  cut 
surface  with  those  in  which  only  old  cells  are  present  shows,  on  the 
whole,  little  difference  between  the  two. 

2.  The  slight  difference  favors  the  new  cells  but  may  not  be 
significant. 

3.  In  Experiment  I  the  specific  length  of  regeneration  at  the 
end  of  6  days  was  0.196  from  old  tissue  and  0.204  from  new  tissue. 

4.  In  the  same  experiment  at  the  end  of  8  days  the  specific 
length  from  the  old  was  0.303  and  from  the  new  0.310. 

5.  In  Experiment  II  the  general  result  was  similar  to  that  in 
Experiment  I.  The  amounts  of  regeneration  in  the  two  cases  are  very 
nearly  equal  and  the  slight  difference  is  in  favor  of  the  new  tissue. 

6.  Experiment  III  shows  that  as  regards  completeness  of  regen- 


25]  RATE    OF   REGENERATION— ZELENY  25 

eration  there  is  again  essential  similarity  between  the  old  tissue  and  the 
new  tissue  levels. 

7.  The  result  strengthens  the  view  that  the  rate  of  regeneration  is 
controlled  in  large  part  by  factors  not  inherent  in  the  character  or  con- 
dition of  the  cells  near  the  cut  surface. 

8.  In  the  case  of  the  earliest  stages,  those  in  which  there  is  cell 
migration  but  no  cell  division,  there  is  some  evidence  that  the  rate  of 
regeneration  may  be  greater  from  new  than  from  old  tissue. 


26  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [26 


PART  II 

THE  EFFECT  OF  SUCCESSIVE  REMOVAL  UPON  THE  RATE 
AND  COMPLETENESS  OF  REGENERATION 

One  of  the  most  interesting  facts  in  connection  with  regeneration 
is  the  ability  to  replace  a  part  after  repeated  removal.  The  present  set 
of  experiments  was  made  in  continuation  of  previous  studies  of  the 
effect  of  successive  removal  upon  the  rate  of  regeneration  (Zeleny  1907, 
1908,  1909).  The  earlier  studies  show  that  as  a  rule  the  rate  of  regen- 
eration following  a  first  removal  is  no  greater  than  that  following  second 
and  later^removals  if  the  effect  of  age  is  eliminated.  Where  a  difference 
exists  it  seems  to  be  in  favor  of  the  later  regeneration's. 

The  matter  is  of  very  great  interest  in  connection  with  general 
problems  of  development  and  particularly  in  connection  with  'the  ques- 
tion as  to  the  existence  or  non-existence  of  a  necessary  limit  to  the 
amount  of  living  substance  that  a  single  individual  may  produce  during 
its  life  cycle.  Does  the  production  of  a  group  of  tissues  use  up  a  part 
of  a  certain  store  of  developmental  energy  or  of  developmental  factors 
possessed  by  the  individual  or  is  this  store  inexhaustible  or  perchance 
even  increased  by  exercise  of  the  function?  These  questions  warrant 
more  extended  study  especially  in  view  of  the  additional  analysis  that 
has  been  made  of  other  factors  controlling  the  rate  of  regeneration. 
The  paper  includes  all  the  unpublished  data  that  have  been  obtained 
on  the  problem  at  hand.  In  general  these  data  support  the  conclusions 
previously  reached.  The  descriptions  of  the  individual  experiments 
will  first  be  given  and  they  will  be  followed  by  a  discussion  of  the  general 
results. 

Experiment  I  Rana  clamitans  Series  3628-3675 
Material  and  Method  The  tadpoles  were  collected  on  December  9, 
1911.  At  the  time  of  the  operation  on  December  20  the  average  total 
length  was  33.0  mm.  and  the  average  tail  length  21.6  mm.  Forty-eight 
individuals  were  divided  into  twelve  sets  of  four  each.  The  four  indi- 
viduals of  a  set  are  called  a,  b,  c,  and  d.  Approximately  one-half  in 
length  of  the  tail  was  removed  by  a  transverse  cut  in  c  and  d.  After 
21  days  the  regenerated  portion  of  the  tail  was  removed.  In  individual 
c  the  second  cut  came  inside  of  the  border  line  between  old  and  new 


27]  RATE    OF    REGENERATION— ZELENY  27 

tissue  arid,  in  individual  d  it  came  outside  of  that  line.  Of  the  two  indi- 
viduals available  for  second  regeneration  in  each  set,  the  one  with  the 
cut  nearer  to  the  tip  of  the  tail  was  chosen  as  individual  c  and  the  other 
as  individual  d.  In  this  way  the  second  regeneration  levels  were  equal- 
ized. A  first  removal  of  a  half  of  the  tail  was  made  in  individuals  a 
and  b  at  the  same  time  that  the  second  removal  was  made  in  c  and  d. 
A  direct  comparison  of  the  rate  of  the  second  regeneration  with  that 
of  the  first  was  thus  made  possible  without  the  complication  due  to 
internal  factors  such  as  difference  in  age,  or  external  factors  such  as 
temperature  and  food. 

Measurements  of  regenerated  lengths  were  made  at  the  end  of 
six  and  of  eight  days,  other  experiments  having  shown  that  the  period 
of  most  rapid  growth  comes  at  about  this  time. 

Elsewhere  there  is  a  comparison  of  the  rate  of  regeneration  from 
new  tissue  with  that  from  old  tissue.  Here  the  chief  concern  is  the 
comparison  of  the  rate  of  the  second  regenerations,  including  both  old 
tissue  and  new  tissue  levels,  with  first  regenerations. 

Data  The  results  of  the  experiment  are  given  in  Table  19  for  six- 
day  regenerations  and  in  Table  20  for  eight-day  regenerations.  At  the 
end  of  six  days  the  average  length  of  first  regenerations  is  2.01  mm. 
and  of  second  regenerations  2.18  mm.  The  first  exceeds  the  second  in 
two  cases,  the  second  exceeds  the  first  in  eight  and  one  is  tied.  The 
corresponding  average  specific  amounts  are  0.194  and  0.205.  In  five 
cases  the  first  exceeds  the  second  and  in  six  the  second  exceeds  the  first. 

At  eight  days  the  average  length  of  the  first  regenerations  is  3.06  mm. 
and  of  the  second  3.42  mm.  The  first  exceeds  the  second  in  three  sets 
and  the  second  exceeds  the  first  in  seven  sets.  The  corresponding  aver- 
age specific  amounts  are  0.298  and  0.323.  In  four  the  first  exceeds  the 
second  regeneration  and  in  six  the  second  exceeds  the  first. 

Comparing  the  first  regenerations  on  the  one  hand  with  second 
regenerations  from  old  tissue  and  on  the  other  hand  with  second  regen- 
erations from  new  tissue  it  is  found,  including  only  complete  sets,  that 
at  the  end  of  six  days  the  average  first  regeneration  length  is  2.01  mm. 
while  that  of  the  second  from  new  tissue  is  2.15  mm.  and  from  old  tissue 
2.16  mm.  The  corresponding  average  specific  amounts  are  0.194  for 
first  regenerations  and  0.196  for  second  regenerations  from  old  tissue 
and  0.204  for  second  regenerations  from  new  tissue. 

At  eight  days  the  first  regeneration  lengths  average  3.06  mm.  while 
second  regenerations  from  old  tissue  average  3.19  and  those  from  new 
tissue  3.12.  The  corresponding  specific  lengths  are  0.298  for  first  regen- 
erations and  0.303  for  second  from  old  tissue  and  0.310  for  second  from 
new  tissue. 


28 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[28 


TABLE  19 

Rana  clamitans       Series  3676-3765 

Comparison  of  first  and  second  regenerations      Age  factor  eliminated 

Six  Days 


Series 


II 


III 


IV 


VI 


VII 


Regen- 
eration 

Total 
length 

Tail 
length 

Length 

re- 
moved 

Lengtr 
regen 
erated 

1 

individual  a 

35.5 

23.1 

11.5 

1.9 

individual  b 

34.5 

21.9 

9.4 

1.8 

2 

c  from  old  tissue 

38.0 

24.1 

13.2 

2.2 

d  from  new  tissue 

39.2 

24.6 

12.8 

2.3 

1 

a 

34.5 

23.0 



— 

b 

33.9 

22.2 

9.6 

1.7 

2 

c  old 

35.7 

23.2 

12.3 

2.0 

d  new 

33.8 

22.1 

10.2 

1.8 

1 

a 

36.2 

23.3 

9.7 

1.7 

2 

b 

34.1 

22.5 

10.9 

1.9 

c  old 

35.8 

23.1 

12.8 

2.0 

d  new 

38.4 

25.0 

11.9 

2.4 

1 

a 

33.1 

21.2 

12.6 

2.2 

2 

b 

32.4 

20.8 

10.2 

1.7 

c  old 

32.9 

20.8 

11.3 

1.7 

d  new 

31.4 

20.4 

9.3 

2.2 

1 

a 

40.8 

27.3 

11.9 

2.1 

2 

b 

39.4 

26.4 

12.7 

2.2 

c  old 

37.5 

23.8 

11.5 

2.2 

d  new 

42.8 

29.2 

15.1 

2.3 

1 

a 

37.0 

24.5 

10.2 

1.9 

b 

35.7 

24.6 

12.9 

2.2 

2 

c  old 

37.0 

25.6 

11.2 

2.3 

d  new 

35.9 

23.3 

9.9 

2.1 

1 

a 

31.2 

20.1  ' 

11.9 

2.1 

b 

28.0 

18.6 

8.4 

2.0 

2 

c  old 

31.3 

20.8 



— 

d  new 

29.0 

19.2 

9.2 

2.4 

Specific 
length 
regen- 
erated 

Aver- 
age 
length 
regen- 
erated 

Aver- 
age 
specific 
length 
regen- 
erated 

0.17 

0.19 

1.85 

0.180 

0.17 
0.18 

2.25 

0.175 

0.18 

1.70 

0.180 

0.16 
0.18 

1.90 

0.170 

0.18 
0.17 

1.80 

0.175 

0.16 
0.20 

2.20 

0.180 

0.17 
0.17 

1.95 
L95 

0.170 

0.15 
0.24 

0.195 

0.18 
0.17 

2.15 

0.175 

0.19 
0.15 

2.25 

0.170 

0.19 
0.17 

2.05 

0.180 

0.21 
0.21 

2.20 

0.210 

0.18 
0.24 

2.05 

0.210 

0.26 

2.40 

0.260 

29] 


RATE    OF    REGENERATION— ZELENY 
TABLE  19   (Continued) 


29 


Series 


VIII 


IX 


X 


XI 


XII 


Average 


Regen- 
eration 


1 


a 

b 

c 

old 

d 

new 

a 

b 

c 

old 

d 

new 

a 

b 

c 

old 

d 

new 

a 

b 

c 

old 

d 

new 

a 

b 

c 

old 

d 

new 

Total 
length 


28.7 

32.0 


31.8 
33.0 


29.8 
26.9 


26.5 
29.4 


32.1 
32.4 


32.7 
30.0 


30.9 
30.1 


31.1 
32.4 


28.0, 
26.3 


24.4 
28.5 


32.7 


33.4 


Tail 
length 


18.5 
21.5 


21.1 
22.0 


19.1 
17.0 


17.0 
19.0 


21.5 
21.5 


22.4 
19.8 


20.9 
20.2 

20.8 
21.8 


18.0 
16.4 

15.4 
18.1 


21.4 


21.8 


Length 

re- 
moved 


10.0 
8.5 


13.2 
11.7 


10.1 
10.7 


9.6 
8.7 


12.0 
10.1 


10.2 
9.4 


9.2 
8.9 


11.0 
10.4 


8.6 
8.7 


10.6 


10.9 


Length 
regen- 
erated 


2.1 

2.2 

2.4 
2.7 


2.3 
2.3 


2.5 
2.0 


2.3 
2.0 


2.0 
1.8 


1.6 
1.8 


2.2 
2.1 


2.7 
1.9 


Specific 
length 
regen- 
erated 


0.21 
0.26 


0.18 
0.23 


0.23 
0.22 


0.26 
0.23 


0.19 
0.20 


0.20 
0.20 


0.17 
0.20 


0.20 
0.20 


0.31 
0.22 


Aver- 
age 
length 
regen- 
erated 


2.17 


2.55 


2.30 


2.25 


2.15 


1.90 


1.70 


2.15 


2.30 


2.01 


2.18 


Aver- 
age 
specific 
length 
regen- 
erated 


0.235 


0.205 


0.225 


0.245 


0.19E 


0.200 


0.185 


0.200 


0.265 


0.194 


0.205 


The  data  as  a  whole  show  an  advantage  in  favor  of  the  second 
regeneration  as  compared  with  the  first.  This  is  seen  not  only  when  the 
direct  regenerated  lengths  are  taken  but  also  when  the  specific  amounts 
are  used.  Elsewhere  it  is  shown  that  the  specific  amount  of  regeneration 
is  independent  of  the  level  of  the  cut  and  therefore  a  constant  within 
the  limits  of  removal  as  used  in  this  experiment.    The  specific  amount 


30 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[30 


determinations  are  therefore  more  accurate  for  our  purposes  than  the 
direct  values  of  length  regenerated. 

The  first  regeneration  is  slightly  below  the  second  not  only  in  case 
the  latter  is  from  new  cells  but  also  in  case  it  is  from  old  cells.  The 
difference  between  first  and  second  regenerations  therefore  can  not  be 
due  entirely  to  the  presence  in  the  former  of  cells  which  are  already 
undergoing  regeneration. 

TABLE  20 

Rana  clamitans       Series  3628-3675 
First  and  second  regenerations  compared      Age  factor  eliminated 

Eight  days 


Series 

Re- 
gener 
ation 

Length 
removed 

Length 
regen- 
erated 

Specific 
length 
regen- 
erated 

Average 
length 
regen- 
erated 

Average 
specific 
length 
regen- 
erated 

1 

individual  a 

11.5 

3.1 

0.26 

I 

individual  b 

9.4 

2.5 

0.27 

0.28 

0.265 

2 

c  from  old  tissue 

13.2 

3.5 

0.27 

d  from  new  tissue 

12.8 

3.1 

0.24 

3.30 

0.255 

1 

a 



— 



b 

9.6 

2.1 

0.22 

2.10 

0.220 

II 

2 

c  old 

12.3 

3.4 

0.28 

d  new 

10.2 

— 



3.40 

0.280 

1 

a 

9.7 

2.7 

0.28 

b 

10.9 

3.4 

0.31 

3.05 

0.295 

III 

2 

c  old 

12.8 

3.25 

0.25 

d  new 

11.9 

3.5 

0.29 

3.37 

0.270 

1 

a 

12.6 

3.25 

0.26 

b 

10.2 

3.25 

0.32 

3.25 

0.290 

IV 

2 

c  old 

11.3 

3.4 

0.30 

d  new 

9.3 

— 



3.40 

0.300 

1 

a 

11.9 

— 



b 

12.7 

4.0 

0.31 

4.00 

0.310 

v 

2 

c  old 

11.5 

— 



d  new 

15.1 

— 







31] 


RATE    OF    REGENERATION— ZELENY 
TABLE  20    (Continued) 


31 


Series 

Re- 
gener- 
ation 

Length 
removed 

Length 
regen- 
erated 

Specific 
length 
regen- 
erated 

Average 
length 
regen- 
erated 

Average 
specific 
length 
regen- 
erated 

1 

a 

10.2 

3.6 

0.35 

VI 

b 

12.9 

3.6 

0.28 

3.60 

0.315 

2 

c  old 

11.2 

3.1 

0.28 

d  new 

9.9 

3.1 

0.31 

3.10 

0.295 

- 

1 

a 

11.9 

3.8 

0.32 

b 

8.4 

3.25 

0.39 

3.52 

0.355 

VII 

2 

c  old 



— 



d  new 

9.2 

3.6 

0.39 

3.60 

0.390 

1 

a 

10.0 

3.25 

0.32 

b 

8.5 

3.4 

0.40 

3.32 

0.36O 

VIII 

2 

c  old 

13.2 

— 



d  new 

11.7 

4.9 

0.42 

4.90 

0.420 

1 

a 

10.1 

3.2 

0.32 

b 

10.7 

3.4 

0.32 

3.30 

0.320 

IX 

2 

c  old 

9.6 

3.5 

0.36 

d  new 

8.7 

3.0 

0.34 

3.25 

0.350 

1 

a 

12.1 

3.6 

0.30 

b 

10.1 

2.3 

0.23 

2.95 

0.265 

X 

2 

c  old 



— 

— — 

• 

d  new 

1 

a 

10.2 

3.5 

0.34 

b 

9.4 

2.5 

0.27 

3.00 

0.305 

XI 

2 

c  old 

9.2 

2.3 

0.25 

d  new 

8.9 

2.5 

0.28 

2.40 

0.263 

1 

a 

11.0 

— 



b 

10.4 

2.7 

0.26 

2.70 

0.260 

XII 

2 

c  old 

8.6 

3.5 

0.41 

d  new 

8.7 

3.5 

0.40 

3.50 

0.405 

1 

10.6 

3.06 

0.298 

Average 

2 

10.9 

3.42 

0.323 

32  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [32 

Experiment  II      Rana  clamitans      Series  3676-3765 

Material  and  Method  Ninety  tadpoles  with  an  average  total  length 
of  about  40  mm.  and  an  average  tail  length  of  27  mm.  were  used  in  the 
experiment.  The  plan  consisted  in  the  removal  of  a  portion  of  the  tail 
in  a  part,  S,  of  the  individuals,  the  remaining  part,  F,  being  left  un- 
injured at  the  time.  After  S  had  been  regenerating  a  new  tail  for 
twenty-two  days  both  S  and  F  were  operated  upon.  In  S  the  regen- 
erating tails  were  removed  by  a  cut  which  came  at  the  border  line  be- 
tween the  old  and  the  new  tissues.  In  F  an  operation  was  made  similar 
to  the  original  one  on  S  and  leaving  the  same  amount  of  old  tail  in  both 
S  and  F.  The  procedure  is  similar  to  that  shown  in  Figure  1.  S  and 
F  were  now  allowed  to  regenerate  and  a  direct  comparison  is  possible 
between  a  second  regeneration  in  S  and  a  first  regeneration  in  F. 

Measurements  were  made  of  regenerated  lengths  at  4,  6,  8,  10,  12y2, 
18  and  56  days.  The  operations  were  made  at  six  levels  corresponding 
approximately  to  the  removal  respectively  of  a/18,  Vio>  %>  %>  Y2 
and  %  of  the  tail.  Four  of  these  levels,  1/10,  %,  ^  and  %,  had  at 
least  five  individuals  each  for  each  regeneration.  The  other  two  levels, 
1/18  and  %,  had  less  than  five  individuals  per  regeneration  but  are 
included  in  the  tables  though  their  averages  are  not  as  reliable  as  those 
of  the  others. 

The  method  as  described  agrees  in  principle  with  that  pursued  in 
Experiment  I.  It  has  a  decided  advantage  over  a  direct  comparison 
within  a  single  individual  because  it  eliminates  the  age  factor  as  well  as 
the  effects  of  change  in  external  conditions  such  as  temperature  and 
food. 

Data  The  results  of  the  experiment  are  given  in  Tables  21  to  30 
an<^  in  Figures  2  and  3.  The  data  show  on  the  whole  a  tendency  for 
the  second  regeneration  to  remain  in  advance  of  the  first  for  eight  or 
ten  days  after  the  operation.  The  first  regeneration  then  catches  up 
and  even  slightly  surpasses  the  other;  this  is  apparent  both  when  the 
regenerated  lengths  are  taken  directly  and  when  they  are  corrected  for 
difference  in  level  of  the  cut  and  put  in  terms  of  specific  regenerated 
length  or  the  length  regenerated  per  unit  of  removed  length. 

In  making  the  comparisons  certain  general  features  must  be  borne 
in  mind.  The  maximum  rate  of  regeneration  is  reached  on  or  near  the 
seventh  day,  earlier  for  the  smaller  removals  and  later  for  the  larger 
removals.  The  whole  regeneration,  in  so  far  as  it  is  completed,  is 
finished  in  nearly  all  cases  at  12^  days,  again  somewhat  earlier  for  the 
smaller  and  somewhat  later  for  the  larger  removals.  In  the  tadpoles 
used  in  the  present  experiment  about  four-tenths  in  length  of  the  re- 
moved tail  is  replaced  before  regeneration  stops.    This  was  found  to  be 


33] 


RATE    OF   REGENERATION— ZELENY 


33 


generally  true  of  tadpoles  of  this  size  in  Rana  clamitans.  The  percent 
regenerated  is  somewhat  greater  for  the  smallest  removals  than  for  the 
others.  After  the  maximum  is  reached  there  is  a  tendency  toward  de- 
crease of  the  regenerated  region  though  this  is  hard  to  determine  with 
accuracy  because  the  boundary  between  old  and  new  tissue  becomes 
more  and  more  obscure  as  time  goes  on.  For  this  reason  the  data  for 
56  days  of  regeneration  are  not  as  reliable  as  the  others. 


mm. 
.400 


to 
8 
o 

s 

"3 

i 


.300 


.200 


.100 


4  6  8         10  12y2  18 

— >■      Days 
Figure  2.    Specific  regenerated  lengths  during  the  regenerative  period  for 
both  first  and  second  regenerations.     Tadpole  tail  of   Rana  clamitans.      Series 
3676-3765. 

Broken  line  =  second  regeneration. 
Unbroken  line  =  first  regeneration. 


'3 
<v 
a 


11% 


15% 


Days 


Figure  3.  Change  in  specific  rate  of  regeneration  during  the  regenerative 
period  for  both  first  and  second  regenerations.  Tadpole  tail  of  Rana  clamitans. 
Series  3676-3765. 

Unbroken  line  =  first  regeneration. 

Broken  line  =  second   regeneration. 


34  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [34 

At  the  four-day  period  the  amount  of  regeneration  is  so  small  that 
there  is  a  large  probable  error  and  these  data  should  be  used  with  cau- 
tion. For  the  1/18  and  %  removals  the  number  of  individuals  is  so 
small  that  the  data  for  these  levels  do  not  compare  in  accuracy  with  the 
others  and  they  will  therefore  be  passed  over  for  the  present. 

The  data  are  presented  in  Tables  21  to  30.  Tables  21  to  26  give 
respectively  the  regenerations  for  the  six  different  levels  beginning  with 
the  shortest  removal.  Table  27  collects  all  the  data  of  amounts  regen- 
erated and  Table  28  all  the  data  of  specific  amounts  regenerated. 
Figure  2  gives  in  graphic  form  the  specific  amounts  regenerated 
for  each  regeneration.  Table  29  gives  the  differences  between 
the  first  and  second  regenerations  for  each  of  the  different  levels  at  each 
of  the  seven  times  of  measurement.  It  includes  the  differences  in  specific 
length  as  well  as  those  in  absolute  length.  The  specific  lengths  furnish 
the  better  basis  for  comparison  and  will  be  used  in  the  following  discus- 
sion unless  otherwise  stated.  Table  30  compares  the  specific  rates  in 
the  first  and  second  regenerations  and  Figure  3  gives  the  results  in 
graphic  form. 

Taking  up  the  regeneration  from  the  different  levels  and  leaving 
out  of  consideration  for  the  present  the  two  levels  with  too  small  a 
number  of  individuals,  the  data  for  the  1/10  level  as  given  in  Table  4 
are  the  first  to  be  considered.  There  are  five  individuals  for  first  and 
seven  for  second  regenerations.  The  second  regeneration  is  ahead  in 
specific  length  from  the  fourth  to  the  tenth  day.  At  121/2  days  the  two 
are  tied  and  at  56  days  the  first  is  ahead.  Regeneration  is  completed  in 
12%  days  and  beyond  this  time  there  is  a  decrease  in  regenerated  ma- 
terial. The  decrease  is  greater  in  the  second  than  in  the  first  regenera- 
tion, hence  the  ascendency  of  the  latter  at  56  days.  During  the  whole 
period  of  active  regeneration  the  second  regeneration  remains  ahead. 

There  are  eight  individuals  for  the  first  regeneration  and  eleven  for 
the  second  at  the  Ys  level  (Table  24).  The  specific  amounts  of  regenera- 
tion are  strikingly  similar  throughout  the  whole  period  of  regeneration. 
The  two  departures  from  equality  are  an  advantage  of  0.01  for  the  second 
regeneration  at  8  days  and  a  disadvantage  of  0.02  at  18  days.  These 
•departures  are  in  the  direction  of  the  general  rule  observed  at  other 
levels  that  the  second  regeneration  tends  to  be  ahead  at  the  earlier  pe- 
riods and  the  first  at  later  periods,  the  advantage  in  the  later  case  being 
due  to  the  earlier  completion  of  regeneration  and  absorption  of  regener- 
ated material  in  the  second  regenerations  than  in  the  first  ones.  In  this 
instance  the  first  regeneration  does  not  gain  an  advantage  until  after  the 
second  has  reached  its  maximum. 

At  the  ^2  level  there  are  5  individuals  for  the  first  regeneration  and 
8  for  the  second  (Table  25).    The  second  is  ahead  until  the  eighth  day. 


35]  RATE    OF    REGENERATION— ZELENY  35 

Beginning  with  the  tenth  day  the  first  is  ahead.  In  general  the  advan- 
tage of  the  first  increases  as  time  goes  on.  The  growth  of  new  tissue 
does  not  terminate  until  the  eighteenth  day  or  after. 

At  the  %  level  there  are  five  individuals  for  the  first  and  ten  for 
the  second  regeneration  (Table  26).  The  second  is  ahead  of  the  first 
until  the  tenth  day,  after  which  the  first  is  in  the  lead.  Regeneration 
is  not  stopped  until  the  eighteenth  day  or  later. 

At  all  four  of  these  levels  the  specific  length  of  the  second  regen- 
eration tends  to  be  ahead  until  the  tenth  day  (Table  28  and  Figure  2). 
The  maximum  rate  of  regeneration  is  reached  before  this  time  and  some- 
what earlier  by  the  second  than  by  the  first  regeneration,  hence  the 
relative  gain  by  the  latter  after  the  tenth  day  (Table  30  and  Figure  3). 
The  stopping  of  regeneration  also  comes  earlier  for  the  second  than  for 
the  first  regeneration  as  does  the  beginning  of  absorption  of  regenerated 
material. 

The  data  in  Experiment  I  concern  the  amount  of  regeneration  at 
six  and  at  eight  days.  At  the  corresponding  times  in  Experiment  II 
the  second  regeneration  is  ahead  of  the  first.  There  is  a  full  agreement 
between  the  two  experiments  in  this  regard. 

The  more  rapid  rate  of  the  second  regeneration  at  the  start  may 
at  first  sight  seem  to  be  due  to  the  presence  of  at  least 
some  cells  which  have  been  actively  engaged  in  previous  regenerations. 
If  the  second  cut  comes  outside  of  the  boundary  between  old  and  new 
cells  the  latter  cover  the  whole  new  cut  surface.  Even  if  the  cut  seems 
to  be  exactly  at  the  original  cut  level  there  will  be  some  new  cells  at 
the  regenerating  surface.  These  cells  which  are  already  regenerating 
may  be  expected  to  adjust  themselves  more  readily  to  the  new  conditions 
than  old  ones  which  have  not  been  engaged  in  such  a  process.  In  another 
place  the  relative  rates  from  old  and  from  new  tissue  are  described 
and  a  slight  early  difference  favoring  the  new  tissue  is  made  out.  While 
this  slight  initial  advantage  may  be  explained  in  this  way  it  is  probably 
confined  to  the  period  of  cell  migration  and  is  not  a  factor  in  the  period 
of  cell  division  which  begins  on  the  second  day  or  later.  It  is  evident 
that  on  the  whole  the  control  of  rate  is  not  a  matter  inherent  in  the 
cells  in  the  neighborhood  of  the  cut  surface.  Indications  point  rather 
to  a  more  central  control  of  the  process. 


36 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[36 


TABLE  21 

Rana  clamitans       Series  3676-3765 

Comparison  of  first  and  second  regenerations      Age  factor  eliminated 

One-eighteenth  of  tail  removed 


Catalog 
number 

Re- 
moved 
length 
mm. 

1.4 

1.7 

1.5 

1.3 
1.6 
1.6 
1.6 

1.5 

Length   regenerated  in  mm. 

4 
Days 

6 
Days 

8 
Days 

10 
Days 

1.0 

0.8 

12* 
Days 

18 
Days 

56 
Days 

First 

3706 
3742 

0.24 
0.30 

0.54 
0.40 

0.9 
0.7 

1.0 
0.9 

0.9 
0.9 

0.7 
0.7 

eration 

Average 

Second 
regen- 
eration 

3676 
3682 
3730 
3754 

0.27 
0.18 
0.39 
0.06 

0.60 
0.60 
0.75 
0.55 

0.9 
0.9 
0.9 
0.9 

1.0 

1.0 
0.9 
1.1 

1.0 
1.0 
0.9 
1.2 

1.0 
1.0 
0.9 
1.2 

0.7 
1.1 
0.7 
1.1 

Average 

Av.  length — First  regen. 

0.27 

0.47 

0.8 

0.9 

0.9 

0.9 

0.7 

Av.  length — Second  regen. 

0.22 

0.62 

0.9 

1.0 

1.0 

1.0 

0.9 

Increase  or  decrease 

—0.05 

+0.15 

+0.1 

+0.1 

+0.1 

+0.1 

+0.2 

Specific  Ig. — First  regen. 

0.17 

0.30 

0.53 

0.58 
0.67 

0.61 

0.60 
0.67 

0.45 

Specific  Ig. — Second  regen. 

0.15 

0.42 

0.60 

0.67 

0.60 

Increase  or  decrease 

—0.02 

+0.12 

+0.07 

+0.09 

4  0.06 

+0.07 

10.15 

37] 


RATE    OF   REGENERATION— ZELENY 


37 


TABLE  22 

Rana  clamitans       Series  3676-3765 

Comparison  of  first  and  second  regenerations      Age  factor  eliminated 

One-tenth  of  tail  removed 


Catalog 
number 

Re- 
moved 
length 
mm. 

2.5 

Length  regenerated 

in  mm. 

4 
Days 

6 
Days 

8 
Days 

10 
Days 

12* 
Days 

18 
Days 

56 

Days 

3688 

0.12 

0.3 

0.3 

0.7 

0.9 

0.9 

0.7 

3707 

3.2 

0.24 

0.8 

1.1 

1.4 

1.4 

1.3 

0.7 

First 

3724 

2.6 

0.06 

0.5 

0.8 

1.1 

1.4 

1.4 

1.2 

regen- 

3743 

2.5 

0.03 

0.1 

0.4 

0.8 

1.0 

1.0 

1.7 

eration 

3760 

3.1 
2.6 
2.0 

0.30 

0.6 

0.9 

1.1 

1.2 

1.1 

1.1 

Average 

3677 

0.30 

0.6 

0.9 

0.9 

0.9 

0.9 

0;7 

3696 

2.1 

0.48 

0.8 

1.0 

1.1 

1.0 

1.0 

0.7 

3713 

2.8 

0.36 

0.8 

0.9 

0.9 

0.9 

0.9 

0.5 

Second 

3719 

3.1 

0.36 

0.8 

1.1 

1.4 

1.4 

1.3 

— 

regen- 

3749 

2.8 

0.30 

0.6 

1.2 

1.4 

1.4 

1.3 

0.9 

eration 

3750 

3.5 

0.48 

1.3 

1.7 

1.9 

2.0 

2.0 

— 

3701 

3.2 
2.8 

0.42 

0.8 

1.1 

1.2 

1.3 

1.3 

— 

Average 

Av.  length— 

-First  regen. 

0.15 

0.5 
0.8 

0.7 

1.0 

1.3 

1.2 

1.1 

1.1 

Av.  length- 

-Second  regen. 

0.39 

1.1 
+0.4 

1.3 
+0.1 

1.2 

0.8 

Increase   or 

decrease 

+0.24 

+0.3 

+0.3 

+0.1 

—0.3 

Specific  lg.- 

-First  regen. 

0.06 

0.18 

0.27 

0.38 

0.46 

0.42 

0.42 

Specific  lg.- 

-Second  regen. , 

0.14 

0.30 

0.39 

0.46 

0.46 

0.43 

0.29 

Increase  or 

decrease 

+0.08 

+0.12 

+0.12 

+0.08 

0.00 

+0.01 

—0.13 

38 


1LLIX0IS    BIOLOGICAL    MONOGRAPHS 


[38 


TABLE  23 

Rana  clamitans       Series  3676-3765 

Comparison  of  first  and  second  regeneration      Age  factor  eliminated 

One-sixth  of  tail  removed 


Catalog 
number 

Re- 
moved 
length 

mm. 

5.3 
4.3 
4.1 

4.6 

5.0 

5.5 
4.7 
4.6 

4.8 

4.9 

Length  regenerated 

in   mm. 

4 
Days 

6 
Days 

8 
Days 

10 
Days 

12i 
Days 

18 
Days 

56 

Days 

First 
regen- 
eration 

3708 
3726 
3762 

0.54 
0.42 
0.57 

1.2 
0.9 

1.0 

1.9 
1.3 
1.2 

2.1 
1.4 
1.5 

2.3 
1.4 
1.7 

2.3 
1.4 
1.8 

1.8 
1.4 
1.4 

Average 

Second 
regen- 
eration 

3678 
3684 
3702 
3720 
3756- 

0.20 
0.15 
0.42 
0.06 
0.36 

0.5 
0.7 
0.8 
0.3 
1.0 

0.9 
1.2 
1.1 
1.3 
1.3 

1.0 

1.4 
1.3 
1.8 
1.7 

1.1 
1.4 
1.3 
2.3 
1.8 

1.1 
1.5 
1.3 
1.9 
1.6 

1.4 
1.3 
2.0 

Average 

Av.  length— 

-First  regen. 

0.51 

1.0 

1.5 

1.7 

1.8 

1.8 

1.5 

Av.  length — 

■Second  regen. 

0.24 

0.7 

1.2 

1.4 

1.6 

1.5 

1.6 

Increase  or 

decrease 

—0.27 

-0.3 

—0.3 

—0.3 

—0.2 

—0.3 

+0.1 

Specific  lg- 

-First  regen. 

0.11 

0.22 

0.33 

0.27 
0.29 

0.39 

0.39 

0.34 

Specific  lg- 

-Second  regen. 

0.05 

0.14 

0.24 

0.33 
—0.06 

0.31 

0.33 

Increase  or 

decrease 

—0.06 

—0.08 

—0.09 

—0.08 

—0.08 

—0.01 

39] 


RATE    OF    REGEXERATIOX—ZELEXV 


39 


TABLE   24 

Rana  clamitans       Series  3676-3765 
Comparison  of  first  and  second  regenerations      Age  factor  eliminated 
One-third  of  tail  removed 


Catalog 
number 

Re- 
moved 
length 

mm. 

u 

;ngth   regenerated 

in  mm. 

4 
Days 

6 
Days 

8 
Days 

10 
Days 

12i 
Days 

18 
Days 

56 

Days 

3690 

9.7 

0.48 

1.0 

1.7 

2.4 

2.6 

2.7 

2.2 

3709 

8.8 

0.48 

1.3 

2.0 

2.6 

3.2 

3.4 

3.3 

3727 

8.3 

0.48 

1.1 

1.6 

2.0 

2.2 

2.2 

2.2 

First 

3745 

10.0 

0.54 

1.8 

2.4 

3.8 

4.4 

4.8 

4.2 

regen- 

3744 

6.0 

0.36 

1.0 

1.3 

1.7 

1.8 

1.7 

— 

eration 

3761 

6.6 

0.39 

1.0 

1.5 

1.9 

2.2 

2.3 

1.8 

3763 

8.5 

0.57 

1.1 

1.8 

2.4 

2.9 

3.1 

— 

3689 

6.3 
8.2 

8.4 

0.30 

0.7 

1.2 

1.5 

1.6 

1.7 

1.4 

Average 

0.30 

3679 

0.7 

1.4 

1.9 

1.9 

2.1 

— 

3685 

9.3 

0.60 

1.2 

1.9 

2.3 

2.8 

3.0 

2.6 

3697 

7.3 

0.48 

1.2 

1.7 

2.2 

2.4 

2.3 

2.1 

3703 

9.3 

0.45 

1.3 

2.0 

2.5 

2.6 

2.5 

2.5 

3715 

7.9 

0.24 

0.9 

1.7 

2.3 

2.6 

2.6 

2.8 

Second 

3721 

8.7 

0.57 

1.3 

1.9 

2.3 

2.6 

2.3 

2.2 

regen- 

3733 

8.5 

0.36 

1.0 

1.9 

2.4 

2.6 

2.6 

2.8 

eration 

3734 

8.5 

0.48 

2.1 

3.1 

4.5 

5.7 

6.4 

6.6 

3739 

9.6 

0.36 

1.0 

1.8 

2.4 

3.0 

2.9 

— 

3751 

6.7 

0.45 

1.1 

1.7 

2.1 

2.4 

2.5 

2.3 

3757 

8.0 
8.4 

0.42 

1.2 

2.1 

2.8 

3.1 

3.2 

3.1 

Average 

Av.  length— 

-First  reg 

en. 

0.45 

1.1 

1.7 

2.3 

2.6 

2.7 

2.5 

Av.  length- 

-Second  re 

gen. 

0.42 

1.1 

1.8 

2.3 

2.6 

2.6 

2.5 

Increase  or 

decrease 

—0.03 

0.0 

+0.1 

0.0 

0.0 

—0.1 

0.0 

Specific  lg.- 

-First  reg 

en. 

0.05 

0.13 

0.21 

0.28 

0.31 

0.33 

0.30 

Specific  lg- 

-Second  r 

egen. 

0.05 

0.13 

0.22 
+0.01 

0.28 

0.31 

0.31 

0.30 

Increase  or 

decrease 

0.00 

0.00 

0.00 

0.00 

—0.02 

0.00 

40 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[40 


TABLE  25 

Rana  clamitans       Series  3676-3765 

Comparison  of  first  and  second  regenerations      Age  factor  eliminated 

One-half  of  tail  removed 


Catalog 
number 

Re- 
moved 
length 

mm. 

12.3 

Length   regenerated 

in  mm. 

4 
Days 

6 
Days 

8 
Days 

10 
Days 

12* 
Days 

18 
Days 

56 
Days 

3710 

0.42 

1.8 

2.9 

3.7 

3.9 

3.9 

3.9 

3728 

12.8 

0.60 

1.7 

2.8 

3.9 

4.8 

5.4 

5.8 

First 

3746 

13.3 

0.54 

1.7 

2.4 

4.1 

5.7 

7.0 

6.8 

regen- 

3764 

14.6 

0.42 

1.3 

2.5 

4.2 

5.3 

6.8 

6.5 

eration 

3765 

12.2 
13.0 
14.5 

0.30 

1.5 

2.3 

3.2 

3.9 

4.5 

4.5 

Average 

3686 

0.60 

2.1 

3.4 

4.8 

5.3 

5.2 

— 

3698 

14.9 

0.50 

1.5 

3.3 

4.3 

5.0 

5.4 

5.4 

3704 

14.5 

0.45 

2.2 

3.3 

4.4 

5.2 

5.5 

5.4 

Second 

3716 

12.7 

0.39 

1.7 

2.4 

3.4 

4.2 

5.1 

4.4 

regen- 

3722 

12.5 

0.60 

1.6 

2.6 

3.6 

3.9 

3.5 

4.2 

eration 

3740' 

13.9 

0.30 

1.1 

2.1 

3.0 

4.6 

5.6 

6.8 

3752 

12.2 

0.54 

1.7 

2.5 

3.4 

4.1 

4.0 

— 

3758 

11.0 
13.1 

0.60 

1.5 

2.2 

2.9 

3.6 

4.1 

4.9 

Average 

Av.  length— 

-First  regen. 

0.46 

1.6 

2.6 

3.8 

4.7 

5.5 

5.5 

Av.  length- 

-Second  regen. 

0.50 

1.7 

2.7 

3.7 

4.4 

4.8 

5.2 

Increase  or 

decrease 

+0.04 

+0.1 

+0.1 

—0.1 

—0.3 

—0.7 

—0.3 

Specific  lg.- 

-First  regen. 

0.03 

0.12 

0.20 

0.29 

0.36 

0.42 

0.42 

Specific  lg.- 

-Second  regen. 

0.04 

0.13 

0.21 

0.28 

0.34 

0.37 

0.40 

Increase  or 

decrease 

+0.01 

+0.01 

+0.01 

-0.01 

—0.02 

—0.05 

—0.02 

41] 


RATE    OF    REGENERATION— ZELENY 


41 


TABLE  26 

Comparison  of  first  and  second  regenerations      Age  factor  eliminated 

Rana  clamitans       Series  3676-3765 

Two-thirds  of  tail  removed 


Catalog 
i   number 

Re- 
moved 
length 

mm. 

16.8 

Length   regenerated 

in  mm. 

4 
Days 

6 
Days 

8 

Days 

10 

Days 

12* 

Days 

18 

Days 

56 

Days 

3692 

0.51 

1.1 

2.2 

3.2 

4.3 

5.0 

5.2 

3693 

17.2 

0.48 

1.8 

3.3 

5.0 

6.5 

7.3 

6.6 

First 

3711 

17.0 

0.54 

1.8 

3.6 

5.6 

7.0 

7.7 

8.3 

regen- 

3729 

16.1 

0.48 

1.9 

3.3 

4.6 

5.5 

6.7 

6.4 

eration 

3749 

16.2 
16.7 
16.0 

0.54 

1.2 

2.7 

4.2 

5.6 

7.1 

7.8 

Average 

3680 

0.60 

1.9 

3.0 

4.2 

5.2 

6.4 

6.6 

3681 

21.2 

0.84 

3.0 

4.0 

5.6 

6.3 

7.3 

7.2 

3687 

19.7 

0.54 

3.6 

5.6 

6.0 

6.6 

7.0 

— 

3699 

21.0 

0.54 

2.2 

4.3 

5.9 

7.1 

7.5 

7.2 

Second 

3705 

17.6 

0.72 

2.0 

3.6 

4.8 

6.4 

6.2 

6.0 

regen- 

3717 

17.6 

0.42 

2.6 

3.6 

5.2 

6.0 

6.7 

6.4 

eration 

3723 

18.4 

0.30 

2.3 

3.7 

5.3 

6.5 

8.1 

8.3 

3735 

16.5 

0.48 

2.0 

3.4 

5.5 

6.5 

7.8 

8.0 

3741 

16.0 

0.30 

1.9 

3.0 

4.4 

5.8 

6.9 

7.0 

3753 

16.8 
18.1 

0.42 

2.0 

2.5 

3.8 

5.2 

6.4 

7.1 

Average 

Av.  length— 

-First  regen. 

0.51 

1.56 

3.02 

4.52 

5.78 

6.76 

6.86 

Av.  length- 

-Second  regen. 

0.52 

2.35 

3.67 

5.07 

6.16 

7.03 

7.09 

Increase  or 

decrease 

+0.01 

+0.79 

+0.65 

+0.55 

+0.38 

+0.27 

+0.23 

Specific  lg.- 

-First  regen. 

0.03 
0.03 
0.00 

0.09 
0.13 

0.18 
0.20 

0.27 

0.35 

0.40 

0.41 

Specific  lg.- 

-Second  regen. 

0.28 

0.34 

0.39 

0.39 

Increase  or 

decrease 

+0.04 

+0.02 

+0.01 

—0.01 

—0.01 

—0.02 

42 


ILLIXOIS    BIOLOGICAL    MOXOGRAPHS 


[42 


TABLE  27 

Rana  clamitans       Series  3676-3765 

Comparison  of  first  and  second  regenerations      Age  factor  eliminated 

Average  lengths  regenerated  in  mm. 


Approx. 

fraction 

of  tail 

removed 


»/. 


'/. 


»A 


»/. 


»A 


V. 


Re- 
gener- 
ation 

Number 
of 

individ- 
uals 

1 

2 

2 

4 

1 

5 

2 

7 

1 

3 

2 

5 

1 

8 

2 

10 

1 

5 

2 

8 

1 

5 

2 

10 

Average 
length 

removed 
in  mm. 


1.5 


1.5 


2.6 


2.8 


4.6 


4.9 


8.2 


8.4 


13.0 


13.1 


16.7 


18.1 


Average   length   regenerated   in   mm. 


4 
Days 


0.3 
0.2 


0.1 


0.4 
0.5 


0.2 
0.4 
0.4 
0.5 
0.5 
0.5 
0.5 


6 
Days 


0.5 


0.6 


0.5 


0.8 


1.0 


0.7 


1.1 


1.1 


1.6 


1.7 


1.6 


2.3 


Days 


0.8 
0.9 


0.7 


1.1 


1.5 


1.2 
1.7 
1.8 
2.6 
2.7 
3.0 
3.7 


10 
Days 


0.9 


1.0 


1.0 


1.3 


1.7 


1.4 


2.3 


2.3 


3.8 


3.7 


4.5 


5.1 


124 
Days 


0.9 


1.0 


1.2 


1.3 


1.8 
1.6 
2.6 
2.6 
4.7 
4.4 
5.8 
6.2 


18 
Days 
i  i 

0.9 

1.0 


1.1 


1.2 


1.8 
1.5 
2.7 
2.6 
5.5 
4.8 
6.8 
7.0 


56 
Days 


0.7 


.0.9 


1.1 

0.8 


1.5 
1.6 
2.5 
2.5 
5.5 
5.2 
6.9 
7.1 


43] 


RATE    OF    REGENERATION— ZELENY 


43 


TABLE   28 
Rana  clamitans       Series  3676-3765 

Comparison  of  first  and  second  regenerations      Age  factor  eliminated 
Specific  lengths  regenerated 


•  Approx. 
fraction 
of  tail 
removed 


»/. 


»A 


v. 


»/. 


»/. 


-/., 


Re- 
gener- 
ation 

Number 

of 
individ- 
uals 

1 

2 

2 

4 

1 

5 

2 

7 

1 

3 

2 

5 

1 

8 

2 

10 

1 

5 

2 

8 

1 

5 

2 

10 

Average 
length 

'emoved 
in  mm. 


1.5 


1.5 


2.6 


2.8 


4.6 


4.9 


8.2 


8.4 


13.0 


13.1 


16.7 


18.1 


All  levels — Average — First 


All   levels — Average — Second 


First  ahead 


Second  ahead 


Specific  length  regenerated  in  mm. 


4 
Days 


0.17 


0.15 


0.06 


0.14 


0.11 


0.05 


0.05 


0.05 


0.03 


0.04 


0.03 


0.03 


0.075 


0.077 


0.002 


6 
Days 


0.30 
0.42 


0.18 


0.30 


0.22 


0.14 


0.13 


0.13 


0.12 


8 
Days 

0.53 


0.60 
0.27 


0.39 
0.33 


0.24 


0.21 


0.22 
0.20 


0.13      0.21 
0.09      0.18 


0.13 


0.173 


0.208 


0.035 


0.20 


0.287 


0.310 


0.023 


10 

Days 


0.58 


0.67 


0.38 


0.46 


0.37 


0.29 


0.28 


0.28 


0.29 


0.28 


0.27 
0.28 


0.362 


0.377 


0.015 


12} 
Days 


0.61 


0.67 


0.46 


0.46 


0.39 


0.33 


0.31 


0.31 


0.36 


0.34 


0.35 


0.34 


0.413 


0.408 


0.005 


18 

Days 


0.60 


0.67 


0.42 


0.43 


0.39 


0.31 


0.33 


0.31 


0.42 


0.37 


0.40 


0.39 


0.427 


56 

Days 


0.45 
0.60 


0.42 


0.29 


0.34 


0.33 


0.30 


0.30 


0.42 


0.40 


0.41 
0.39 


0.413 


0.014 


0.390 


0.385 


0.005 


44 


ILLINOIS   BIOLOGICAL    MONOGRAPHS 


[44 


©  .S 

cm    u 

o> 

B   03 

n 

*  9 

a 
a 


*    I 

o  .2 

§  ■ 

CO      t., 

oi   d 
M  S, 


si 

1  8 

•*->  01 
ca    w 

(h 

0)    T3 

e  m 

bo 

■d  <d 
o   d 

O  CD 
<P  o> 
to     [S 

■g  * 

s* 

+j     01 

w    o 

s  a 

td   o> 


1=1  S 
O  H 


A 

3 
o 

o 


5  J 

•o  IS 

§  E 


N 

co 

CO 

tH 

rH 
O 

O 
+ 

O 

4- 

o 

.    1 

o 

1 

o 

+ 

O 
1 

+ 


+ 


a  c 
o  t> 

o    60 
C/3  ^ 

£    60 

to  g 

rH 

© 

.    + 

t- 

© 

© 

+ 

rH 
© 
+ 

r-i 

© 
© 

+ 

co 
© 

00 

© 
© 

1 

1-j 

1     1 

cm 

© 
© 

© 

1 

© 
o 

1 

C4 

© 

+ 

**    r 

© 

© 

1 

rH 
© 

+ 

00 

© 
© 

+ 

+0.1 
0.00 

1  © 

1    1 

CO 

© 

© 

1 

© 

© 

i 

o 
© 
© 

co 
© 

1 

CM 

© 
© 

1 

o 

+ 

© 
©' 

1 

o 

CO 

00 

o 

CO 

00 

© 

© 

© 
o 

t4 

rH 

© 

CO 

»-H      f 

© 

o 

© 

o 

© 

© 

© 

© 

© 

© 

© 

© 

+ 

+ 

+ 

1 

1 

]  1 

1  I 

+ 

+ 

r^ 

o 

•"* 

CM 

rH 

CO 

© 
© 

rH 

© 

y-i 

© 

t- 

cq  r 

© 

© 

© 

© 

© 

© 

© 

© 

O 

© 

© 

© 

© 

|   + 

+ 

1  + 

+ 

1 

1 

+ 

+ 

i   + 

+    1 

+ 

+  J 

rH 

rH 

CO 

cm    ' 

■r-i 

CO 

00 

© 

o 

© 
© 

y-i 

© 

t- 

© 

© 

+ 

© 
+ 

o 

+ 

© 
+ 

© 

1 

© 

1 

© 

1 

o 

© 
+ 

© 
+ 

© 
+ 

© 

1  rH 

CM 

© 

CO 

00 

© 

CO 

CO 

© 

© 

© 

© 

rH 
© 

© 

© 
© 

© 
J     1 

© 

1 

© 
+ 

o 

i  + 

© 

1 

© 

© 

© 

© 

© 

© 

© 

1  a 

1  s 

a 

a 

A 

a 

-i-> 

a 

A    I 

a 

bfi 

d 

a 

OX) 

d 

a 

bo 

d 

a 

bJD 

a 

bO 

d 

a 

b« 

p 

d 

9 

d 

<u 

d 

o> 

d 

cu 

d 

o> 

d 

0> 

A 

o 
td 

A 

o 

td 

o 

td 

,d 

o 

td 

J3 

o 
td 

o 
td 

bfi 

o 

bo 

o 

bO 

o 

bO 

o 

bO 

o 

bO 

o 

d 

<D 

d 

01 

d 

9 

d 

o> 

d 

0> 

d 

cu 

o> 

Pi 

Ol 

n 

B 

P. 

9 

P< 

0) 

Pi 

o> 

o< 

►J 

m 

A 

w 

J 

OQ 

J 

m 

rJ 

02     1 

hJ 

W 

1115! 


x    - 

8.2 

TJ 

o«l 

a  rt 

<i 

V 

r- 

45] 


RATE    OF    REGENERATION— ZELENY 


45 


TABLE  30 

Rana  clamitans       Series  3676-3765 
Specific  rates  of  first  and  second  regenerations  during  each  of  the  time  periods 


Approx. 

fraction 

of   tail 

removed 


'/. 


I/. 


-/., 


V. 


1/ 


»/. 


Re- 
gener- 
ation 


Num- 
Der  of 
indi- 
viduals 


10 


10 


Average 
length 

removed 
in  mm. 


1.5 


1.5 


2.6 


2.8 


4.6 


4.9 


8.2 


8.4 


13.0 


13.1 


16.7 


18.1 


All  levels — Average — First 


All  levels — Average — Second 


First  ahead 


Second  ahead 


Specific  rate  of  regeneration 


0-4 
Days 


0.042 


0.037 


0.015 


0.035 


0.027 


0.012 


0.012 


0.012 


0.007 


0.010 


0.007 


0.007 


0.018 


0.019 


0.001 


4-6 
Days 


0.065 


0.135 


0.040 


0.080 


0.055 


0.045 


0.040 


0.040 


0.045 


0.045 


0.030 


0.050 


0.046 


0.066 


0.020 


6-8 
Days 


0.115 


0.090 


0.045 


0.045 


0.055 


0.050 


0.040 


0.045 


0.040 


0.040 


0.045 


0.035 


0.057 


0.051 


0.006 


8-10 
Days 


0.025 


0.035 


0.055 


0.035 


0.020 


0.025 


0.035 


0.030 


0.045 


0.035 


0.045 


0.040 


0.037 


0.033 


0.004 


10-12J 
Days 


0.015 


0.000 


0.040 


0.000 


0.010 


0.025 


0.015 


0.015 


0.035 


0.030 


0.040 


0.030 


0-026 


0.017 


0.009 


12i-18 
Days 

18-56 
Days 

—0.002 

—0.004 

0.000 

—0.002 

—0.007 

—0.001 

—0.005 

—0.004 

0.000 

—0.001 

—0.004 

0.001 

0.004 

—0.001 

0.000 

—0.000 

0.011 

0.000 

0.005 

0.001 

0.009 

4-0.000 

0.009 

0.000 

0.002 

—0.001 

0.001 


0.001 


—0.001 


46  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [46 

Experiment  III      Amblystoma  punctatum      Series  3962-3999 

Material  and  Method  Eggs  of  Amblystoma  punctatum  in  the  cleav- 
age stages  were  collected  on  March  18,  1913,  and  hatched  in  the  labo- 
ratory on  April  9.  The  first  operations  were  made  on  April  23, 
at  which  time  also  five  controls  were  killed  and  preserved.  These  when 
measured  gave  an  average  total  length  of  13.1  mm.  and  an  average  tail 
length  of  5.3  mm.  Ninety  individuals  were  used  for  the  regeneration 
study.  In  thirty  individuals  two-thirds  in  length  of  the  tail  was  re- 
moved on  April  23.  The  regenerated  portion  in  these  was  removed 
on  May  10  and  at  the  same  time  in  a  second  thirty  individuals  two- 
thirds  of  the  tail  was  removed.  On  May  21  the  first  thirty  were 
operated  on  for  the  third  time,  the  second  thirty  for  the  second  time, 
and  the  third  thirty  for  the  first  time.  To  insure  as  accurate  a  compari- 
son as  possible  the  ninety  individuals  though  they  were  approximately 
of  equal  size  were  divided  into  thirty  groups  of  three  each,  a  selection 
being  made  so  that  the  three  members  of  a  group  were  as  much  alike 
as  possible.  In  each  group  one  of  the  three  members  was  used  for  the 
first  regeneration,  one  for  the  second  and  the  third  for  the  third  regen- 
eration. This  procedure  gave  a  possibility  of  comparing  the  first,  second 
and  third  regenerations  without  error  due  to  difference  in  size,  age,  or 
in  external  conditions. 

Three  individuals  from  each  thirty  were  killed  two  days  after  the 
last  operations,  'four  in  four  days,  five  in  six  days,  five  in  eight  days, 
six  in  ten  days  and  seven  in  fourteen  days. 

At  the  end  of  the  experiment,  control  individuals  gave  an  average 
total  length  of  31.5  mm.  and  an  average  tail  length  of  10.5  mm. 

Data  The  data  are  given  in  Tables  31  and  32.  The  specific  amounts 
of  regeneration  were  not  determined  because  the  removed  lengths  were 
alike  and  hence  the  comparison  of  absolute  lengths  gives  the  same  re- 
sults as  a  comparison  of  specific  amounts. 

The  average  regenerated  lengths  at  each  of  the  six  different  times 
will  be  taken  up  first.  At  two  days  the  average  regenerated  lengths 
for  the  first,  second  and  third  regenerations  are  respectively  0.22,  0.25 
and  0.26  mm.  At  four  days  the  corresponding  amounts  are  0.66,  0.75 
and  1.00.  At  six  days  they  are  1.36,  1.40  and  1.36,  but  the  low  value 
of  the  third  regeneration  is  due  to  a  single  exceptional  individual.  At 
eight  days  the  figures  are  2.18,  2.68  and  2.68.  At  ten  days  they  are 
3.55,  3.82  and  4.20  and  at  fourteen  days  5.34,  6.12  and  6.08.  In  all 
cases,  except  the  one  at  six  days  explained  above,  both  second  and  third 
regenerations  are  ahead  of  the  first.  The  third  regeneration  is  greater 
than  the  second  at  two,  four  and  ten  days,  is  equal  to  the  second  at  eight 
days  and  less  than  the  second  at  six  and  fourteen  days.    Since  the  low 


47] 


RATE    OF    REGENERATION— ZELENY 


47 


average  for  the  third  regeneration  at  six  days  is  due  to  a  single  excep- 
tional individual  it  is  more  proper  to  put  the  third  ahead  of  the  second 
at  this  time. 

A  comparison  of  the  three  regenerations  by  individual  cases  is 
shown  in  Table  32.  At  each  of  the  six  times  taken  the  number  of  cases 
showing  a  more  rapid  regeneration  is  greater  for  the  third  regeneration 
than  for  the  first  and  also  greater  for  the  second  than  for  the  first.  The 
third  is  ahead  of  the  second  at  two  times  (more  properly  three  times) 
and  equal  to  the  third  at  four  times  (more  properly  three). 

When  all  the  individual  cases  are  taken  together  both  third  and 
second  regenerations  are  again  distinctly  ahead  of  the  first  as  shown 
by  the  totals  in  Table  32.  The  third  is  ahead  of  the  second  in  twelve 
cases  (more  properly  thirteen)  and  the  second  ahead  of  the  first  in  eight 
cases  (more  properly  seven). 

Each  of  the  three  comparisons  shows  that  both  second  and  third 
regenerations  are  more  rapid  than  first  regenerations.  The  third  regen- 
eration shows  a  slight  advantage  over  the  second  instance  in  all  three 
of  the  comparisons.  In  this  instance  the  difference  can  not  be  due 
to  the  presence  of  newly  regenerated  cells  in  the  one  case  and  not  in  the 
other. 

TABLE  31 

Amblystoma  punctatum      Series  3967-3998 

Comparison  of  lengths  of  first,  second  and  third  regenerations 

Age  factor  eliminated 


Regener- 
ation  time 
in 
days 


Catalog 
number 


3967 
3968 
3969 


Average 

3970 
3971 
3972 
3973 

Average 


Regenerated  lengths  in  mm. 


First 
regeneration 

Second 
regeneration 

0.2 

0.25 

0.2 

0.25 

0.3 

0.2 

0.22 

0.25 

0.75 
0.7 
0.5 
0.7 

0.9 

0.75 
0.6 

0.66 

0.75 

Third 
regeneration 


0.3 

0.27 

0.2 


0.26 

1.0 
1.6 

0.8 
0.6 

1.00 


48 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[48 


TABLE  31   (Continued) 

Amblystoma  punctatum       Series  3967-3998 

Comparison  of  lengths  of  first,  second  and  third  regenerations 

Age  factor  eliminated 


Regener- 

Regenerated lengths  in  mm. 

ation   time 
in 

Catalog 
number 

First 

Second 

Third 

days 

regeneration 

regeneration 

regeneration 

3974 

1.2 

1.2 

— 

3975 

1.4 

1.5 

1.5 

3976 

1.3 

1.4 

1.6 

6 

3977 

1.5 

1.2 

0.6 

3978 

1.4 

1.7 

1.7 

Average 

1.36 

1.40 

1.36 

3980 

1.7 

2.4 

2.7 

3981 

1.9 

— 

2.9 

3982 

2.3 

2.6 

3.0 

8 

3984 

2.4 

2.8 

2.1 

3985 

2.6 

2.9 

2.7 

Average 

2.18 

2.68 

2.68 

.  3986 

4.1                            3.8 

4.7 

3987 

3.6 

3.7 

— 

3988 

3.5 

— 

3.9 

3989 

2.6 

3.9 

3.5 

10 

3990 

3.2 

4.25 

4.6 

3991 

4.3 

3.5 

4.35 

Average 

3.55 

3.82 

4.20 

3992 

5.5 

5.5 

5.7 

3993 

5.0 

5.75 

5.7 

3994 

— 

6.7 

6.9 

3995 

5.0 

5.7 

6.9 

14 

3997 

6.9 

6.7 

5.2 

3998 

4.3 

6.35 

— 

Average 

5.34                          6.12 

6.08 

49] 


RATE    OF    REGENERATION— ZELENY 


49 


TABLE  32 

Amblystoma    punctatum       Series    3967-3998       Age    factor    eliminated 

Comparison  of  lengths  of  first,  second  and  third  regenerations 

Comparison  of  individual  cases 


Comparisons 

3rd  regen.  > 1st 
3rd  regen.  =  1st 
3rd  regen. <  1st 

2nd  regen.  >  1st 
2nd  regen.  =  1st 
2nd  regen.  <  1st 

3rd  regen.  >  2nd 
3rd  regen.  =  2nd 
3rd  regen.  <  2nd 


Two 

Four 

Six 

Bight 

Ten 

Fourteen 

days 

days 

days 

days 

days 

days 

2 

3 

3 

4 

5 

3 

1 

0 

0 

0 

0 

0 

0 

1 

1 

1 

0 

1 

2 

2 

3 

4 

3 

3 

1 

0 

1 

0 

0 

1 

0 

1 

1 

0 

2 

1 

1 

2 

1 

2 

3 

3 

1 

1 

2 

0 

0 

0 

1 

0 

1 

2 

1 

3 

Totals 

20 

1 
4 

17 
3 
5 

12 
4 
8 


Experiment  IV      Amblystoma  punctatum      Series  3962-3999 

The  series  used  for  Experiment  III  furnishes  another  set  of  data 
for  the  effect  of  successive  removal.  When  the  third  operation  was  made 
the  removed  regenerated  tails  of  the  first  thirty  individuals  represented 
an  eleven-day  second  regeneration  and  those  of  the  second  thirty-indi- 
viduals an  eleven-day  first  regeneration.  A  direct  comparison  is  thus 
possible  between  the  first  and  the  second  regenerations.  It  is  not  possi- 
ble to  make  a  cut  exactly  at  the  border  line  between  old  and  new  tissue 
and  therefore  the  measurement  of  the  removed  regenerating  tail  is  not 
as  accurate  a  determination  as  is  the  direct  measurement  of  a  regener- 
ating unremoved  tail. 

The  data  are  shown  in  Table  33.  Twenty-five  individuals  are  avail- 
able for  each  regeneration.  The  average  of  the  first  regenerations  is 
4.55  ^.11  and  of  the  second  regenerations  4.50  ±0.10.  The  first  regen- 
eration is  ahead  of  the  second  in  ten  cases,  the  second  is  ahead  of  the 
first  in  twelve  cases  and  three  cases  are  equal.  The  first  comparison 
shows  a  slight  difference  in  favor  of  the  first  regeneration  but  this  is 
so  much  less  than  the  probable  error  that  it  can  not  be  considered  as 
significant.  The  second  comparison  shows  a  slight  advantage  in  favor 
of  the  second  regeneration.  On  the  whole  the  data  indicate  essential 
equality  between  the  first  and  the  second  regenerations  at  eleven  days. 


50 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[50 


TABLE  33 

Amblystoma  punctatum       Series  3962-3999      Age  factor  eliminated 

Comparison  of  first  and  second   regenerations 

Eleven  days 


First 

Second 

First 

Second 

First 

Catalog 

regen. 

regen. 

ahead 

ahead 

and  second 

number 

mm. 

mm. 

of  second 

of  first 

equal 

3967 

4.0 

4.4 

0.4 

3968 

3.7 

3.5 

0.2 

3969 

4.9 

5.1 

0.2 

3970 

4.5 

4.7 

0.2 

3972 

4.7 

4.7 

* 

3973 

3.9 

4.3 

0.4 

3975 

4.5 

5.7 

1.2 

3976 

4.9 

4.9 

* 

3977 

3.8 

3.7 

0.1 

3978 

4.1 

4.5 

0.4 

3980 

4.9 

5.0 

0.1 

3981 

3.5 

4.4 

1.1 

3982 

5.0 

4.7 

0.3 

3984 

5.1 

4.0 

1.1 

3985 

5.8 

4.3 

1.5 

3986 

3.8 

4.1 

0.3 

3989 

4.8 

5.5 

0.7 

3990 

•5.5 

4.3 

1.2 

3991 

4.1 

4.6 

0.5 

3992 

4.6 

4.1 

0.5 

3993 

4.5 

4.5 

* 

3994 

4.9 

5.0 

0.1 

3995 

4.5 

4.0 

0.5 

3997 

5.1 

4.2 

0.9 

3998 

4.8 

4.3 

0.5 

4.55±0.11 

4.50±0.10 

ten 
times 

twelve 
times 

three 
times 

Experiment  V  Amblystoma  punctatum  Series  6042-6100F 
This  series  was  devised  for  a  study  of  the  effect  of  repeated  removal 
of  the  tail  upon  the  rate  of  metamorphosis.  The  removed  tails  were 
preserved  and  they  give  some  data  on  the  comparison  of  successive 
regenerations.  The  interest  of  the  results  lies  in  the  fact  that  the  suc- 
cessive regenerations  are  compared  within  single  individuals.  Thus  the 
effect  of  the  age  factor  is  not  eliminated.  Environmental  differences 
such  as  those  of  temperature  may  also  be  factors. 

The    eggs    were    hatched    on    March    25    to    29,    1915.     Approxi- 
mately one-half  in  length  of  the  tail  was  removed  in  each  of  the  indi- 


51]  RATE    OF   REGENERATION— ZELENY  51 

viduals  on  April  5.  The  new  tissue  was  removed  on  April  17  and 
again  on  May  1,  May  10  and  May  19,  making  five  removals  in  all. 
The  second  removal  gives  the  first  regeneration,  the  third  the  second, 
and  so  on.  The  regenerated  lengths  were  therefore  determined  by 
measurement  of  removed  parts.  This  does  not  give  as  accurate  a  deter- 
mination as  does  direct  measurement  without  removal  because  the  cut 
can  not  in  ordinary  practice  be  made  exactly  at  the  border  line  between 
old  and  new  tissue. 

The  data  are  given  in  Table  34.  The  first  regeneration  covers  a 
twelve-day  period,  the  second  fourteen  days  and  the  third  and  fourth 
each  nine  days. 

The  third  and  fourth  regenerations  are  the  only  ones  that  have  the 
same  time  interval.  Ten  individuals  are  available  for  this  comparison. 
The  average  for  the  third  regeneration  for  these  ten  is  1.30  mm.  and 
of  the  fourth  regeneration  1.17  mm.  When  all  individuals  are  taken 
without  regard  to  representation  of  both  regenerations  the  average  for 
the  third  regeneration  is  1.28  and  for  the  fourth  1.17.  In  seven  of  the 
ten  former  cases  the  third  is  ahead  of  the  fourth  regeneration,  in  two 
they  are  tied  and  in  one  the  fourth  is  ahead  of  the  third.  The  data 
therefore  show  an  advantage  of  the  third  over  the  fourth  regeneration. 

The  first  regeneration  ran  twelve  days  and  the  second  fourteen 
days.  The  maximum  rate  of  regeneration  comes  on  or  near  the  ninth 
day  and  the  rate  has  declined  to  a  low  point  by  the  fourteenth  day. 
However  it  is  not  possible  to  make  the  necessary  correction  because  of 
lack  of  data  on  the  rate  curve  for  this  particular  set  of  larvae.  Some 
facts  may  however  be  obtained  by  a  comparison.  Sixteen  individuals 
for  each  of  the  two  regenerations  are  available  for  comparison.  The 
average  for  the  first  regeneration  in  these  is  2.06  mm.  and  for  the  sec- 
ond 2.01  mm.  In  seven  the  first  is  ahead  of  the  second,  in  seven  the 
second  is  ahead  of  the  first,  and  two  are  tied.  When  all  individuals 
are  taken  without  regard  to  representation  of  both  regenerations  the 
average  for  the  first  regeneration  is  1.99  ±0.03  mm.  for  a  twelve-day 
period  and  for  the  second  regeneration  2.01  for  a  fourteen-day  period. 
The  difference  between  the  two  values  is  not  significant,  but  when  the 
longer  time  interval  taken  by  the  second  regeneration  is  considered  the 
conclusion  is  reached  that  the  first  regeneration  is  more  rapid  than  the 
second. 

The  data  thus  indicate  a  progressive  decrease  in  rate  from  the 
first  to  the  fourth  regenerations.  This  result  taken  in  connection  with 
the  results  obtained  from  the  experiments  in  which  the  age  factor  is 
eliminated  makes  it  highly  probable  that  the  decrease  in  rate  of  regen- 
eration observed  here  is  due  to  increase  in  age  and  not  to  the  effect  of 
successive  removal. 


52 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[52 


TABLE  34 

Amblystoma  punctatum      Series  6042-6100  F      Age  factor  eliminated 
Successive  regenerations  in  single  individuals 


First 

Second 

Third 

Fourth 

regeneration 

regeneration 

regeneration 

regeneration 

Catalog 

mm. 

mm. 

mm. 

mm. 

number 

Twelve 

Fourteen 

Nine 

Nine 

days 

days 

days 

days 

6042 

2.0 

2.4 

1.6 

6043 

1.8 

2.5 

1.5 

1.4 

6044 

2.2 

6046 

2.2 

2.2 

1.3 

1.3 

6047 

2.2 

2.1 

1.4 

1.3 

6048 

2.0 

2.2 

6049 

2.3 

1.8 

1.5 

1.0 

6050 

1.8 

6052 

2.0 

6053 

1.9 

6055 

1.9 

6056 

1.7 

6057 

2.0 

6058 

2.0 

6059 

1.9 

6061 

1.5 

6062 

2.3 

6065 

1.5 

6067 

1.6 

6068 

1.6 

6071 

2.0 

6072 

1.9  . 

6076 

2.1 

6077 

2.0 

6079 

2.0 

6080 

1.8 

6081 

1.9 

6082 

1.9 

2.0 

1.0 

1.1 

6083 

2.0 

2.1 

1.3 

1.1 

6084 

1.9 

6085 

2.0 

2.0 

1.5 

1.5 

6086 

2.2 

6087 

1.8 

1.0 

0.8 

6088 

2.1 

2.4 

1.4 

1.2 

6090 

2.5 

6093 

2.3* 

2.2 

1.0 

0.8 

6094 

2.1 

53] 


RATE    OF    REGENERATION— ZELENY 
TABLE  34  (Continued) 


53 


First 

Second 

Third 

Fourth 

regeneration 

regeneration 

regeneration 

regeneration 

Catalog 

mm. 

mm. 

mm. 

mm. 

number 

Twelve 

Fourteen 

Nine 

Nine 

days 

days 

days 

days 

6096 

2.1 

6097 

2.5 

1.6 

6098 

1.8 

2.1 

6099 

2.2 

' 

6100D 

2.0 

6100E 

1.8 

1.6 

6100F 

2.2 

2.0 

1.1 

1.0 

Average 

1.99  ±0.03 

2.01 

1.28 

1.17 

Rate  per  day 

0.166 

0.144 

0.142 

0.130 

Experiment  VI      Bufo  americanus      Series  6283-6323 

This  series  was  designed  for  the  study  of  the  effect  of  successive 
removal  of  the  tail  upon  the  rate  of  metamorphosis.  The  lengths  of 
the  removed  regenerating  tails  however  are  of  some  value  in  a  com- 
parison of  successive  regenerations  though  here  as  in  Experiment  V 
age  and  external  factors  are  not  eliminated. 

The  eggs  were  laid  on  April  20-21,  1915.  The  tadpoles  were  col- 
lected on  April  27  and  the  first  removals  were  made  on  April  28. 
The  first  metamorphosis  was  completed  on  June  11.  The  average 
total  length  at  the  time  of  the  first  removal  was  10.9  mm.  and  the 
average  tail  length  6.4  mm.  The  average  removed  length  was  3.8  mm., 
which  is  approximately  60  per  cent  of  the  tail  length.  The  second 
removal  was  made  on  May  7  and  gives  a  nine-day  period  for  the  first 
regeneration.  The  third  removal  of  May  17  gives  a  ten-day  period 
for  the  second  regeneration.  The  fourth  removal  on  May  26  gives  a 
nine-day  period  for  the  third  regeneration.  As  in  the  case  of  Experi- 
ment V  the  cuts  could  not  in  practice  be  made  to  come  exactly  at  the 
border  line  between  old  and  new  tissue  and  the  accuracy  of  the  meas- 
urements is  therefore  not  as  great  as  in  those  cases  in  which  the 
lengths  were  taken  directly  from  the  animal  without  removal  of  the  tail. 

The  data  are  shown  in  Table  35.  The  first,  second  and  third  re- 
generation lengths  are  given  for  sixty  individuals.  The  first  and  third 
regenerations  have  the  same  time  interval  and  are  therefore  directly 
comparable.     The  average  for  the  first  regeneration  is  1.94  ^0.02  mm. 


54 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[54 


and  for  the  third  1.80  ^0.03  mm.,  a  difference  in  favor  of  the  first  re- 
generation of  0.14  ±0.05  mm.  This  represents  a  regeneration  of  0.51  mm. 
per  unit  of  removed  length  in  the  first  regeneration  and  0.47  mm.  per 
unit  in  the  third  regeneration.  A  comparison  of  individual  cases  shows 
that  the  first  regeneration  is  ahead  of  the  third  in  36  individuals,  the 
third  is  ahead  of  the  first  in  18  individuals  and  5  are  tied.  The  differ- 
ence between  the  two  regenerations  is  thus  probably  significant.  As  in 
Experiment  V  the  decrease  is  probably  due  to  the  age  factor. 

The  second  regeneration  has  a  time  interval  of  ten  days,  one  day 
more  than  the  first  and  third  regenerations.  In  the  absence  of  know- 
ledge concerning  the  rate  curve  for  toad  tadpoles  of  this  age  no  cor- 
rection can  be  applied.  The  rates  per  day  for  the  three  regenerations 
are  however  given  in  the  table. 


TABLE  35 
Bufo  americanus       Series   6283-6323      Age  factor  not  eliminated 
Successive  regenerations  of  tail 


First 

Second 

Third 

Catalog 

regeneration 

regeneration 

regeneration 

number 

Nine  days 

Ten  days 

Nine  days 

Length  in  mm. 

Length  in  mm. 

Length  in  mm. 

6283  a 

2.1 

2.0 

1.9 

b 

1.5 

2.1 

1.6 

c 

1.7 

2.1 

1.7 

6285  a 

2.3 

1.9 

2.0 

b 

2.3 

2.1 

2.0 

c 

2.0 

2.4 

2.4 

6287  a 

1.9 

2.1 

2.1 

b 

2.1 

2.0 

1.9 

c 

1.8 

2.3 

1.8 

6289  a 

1.9 

2.3 

2.2 

b 

2.1 

2.0 

1.7 

c 

2.2 

2.1 

2.0 

6291  a 

2.1 

2.2 

2.0 

b 

1.9 

1.9 

1.8 

c 

2.0 

1.9 

1.4 

6295  a 

2.0 

Z.O 

2.U 

b 

2.1 

2.1 

1.8 

c 

1.8 

1.9 

1.9 

6297  a 

1.9 

2.0 

2.0 

b 

1.9 

2.1 

1.8 

c 

1.9 

2.0 

1.8 

6299  a 

1.8 

2.0 

1.5 

b 

2.0 

2.0 

1.7 

55] 


RATE    OF    REGENERATION— ZELENY 
TABLE  35   (Continued) 


55 


First 

Second 

Third 

Catalog 
number 

regeneration 

Nine  days 

Length  in  mm. 

regeneration 

Ten  days 

Length  in  mm. 

regeneration 

Nine  days 

Length  in  mm. 

c 

1.8 

1.9 

1.3 

6301  a 

2.0 

1.5 

1.4 

b 

1.8 

1.9 

1.2 

c 

1.7 

1.8 

1.4 

6303  a 

1.9 

1.9 

1.3 

b 

1.9 

1.9 

1.5 

c 

1.8 

2.0 

1.6 

6305  a 

1.9 

2.0 

1.5 

b 

1.7 

1.8 

2.0 

c 

2.1 

2.2 

1.9 

6307  a 

2.1 

1.8 

2.0 

b 

1.9 

2.0 

2.1 

c 

1.8 

1.9 

1.8 

6309  a 

2.0 

1.9 

1.9 

b 

1.9 

1.9 

2.0 

c 

2.0 

2.0 

1.7 

6311  a 

1.7 

2.4 

1.8 

b. 

1.8 

1.9 

2.1 

c 

2.0 

2.1 

2.0 

6313  a 

2.0 

2.3 

1.7 

b 

1.8 

1.7 

2.0 

c 

1.7 

1.7 

1.5 

6315 'a 

1.9 

2.4 

2.0 

b 

2.0 

2.1 

1.6 

c 

1.9 

1.9 

6317  a 

1.9 

2.0 

1.3 

b 

1.8 

2.2 

2.0 

c 

1.9 

2.1 

1.8 

6319  a 

2.2 

2.0 

2.0 

b 

2.1 

2.0 

2.0 

c 

1.9 

1.9 

2.0 

6321  a 

•      2.3 

2.0 

1.8 

b 

1.7 

2.0 

1.9 

c 

2.0 

2.3 

1.3 

6323  a 

2.1 

2.1 

1.7 

b 

1.8 

2.3 

2.0 

c 

1.9 

2.2 

2.0 

Average 

1.94±0.02 

2.02±0.02 

1.80  ±0.03 

Rate  per  day 



0.216 

0.202 

0.200 

56 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[56 


Experiment"  VII  Rana  clamitans  Series  3557-3624 
This  experiment  deals  with  the  relative  completeness  of  regenera- 
tion after  successive  removals  within  single  individuals.  Age  and  ex- 
ternal factors  are  not  eliminated.  A  more  complete  description  of  the 
experiment  is  given  under  "Completeness  of  Regeneration."  The  tail 
length  averaged  approximately  17.0  mm.  About  one-half  of  the  tail 
was  removed  at  the  first  operation.  At  succeeding  operations  the  cut 
came  as  near  as  possible  to  the  border  line  between  old  and  new  tissue. 
The  first  removals  came  on  October  23,  1911,  the  second  on  November 
28,  the  third  January  3,  the  fourth  February  9,  the  fifth  March  16  and 
the  sixth  April  4.  At  the  time  of  the  last  removal  the  hind  legs  were 
just  starting  to  grow. 

The  data  are  given  in  Table  36.  The  first  regeneration  interval  is 
36  days,  the  second  36,  the  third  37,  the  fourth  36  and  the  fifth  39 
days.  Each  one  of  these  is  more  than  sufficient  for  the  completion  of 
the  regenerative  process.  The  individuals  are  divided  into  three  sets, 
A,  B,  and  C.  A,  with  seven  individuals,  has  no  record  for  the  first  regen- 
eration; the  second  regeneration  is  9.8  mm.,  the  third  9.3,  the  fourth 
8.5  and  the  fifth  8.6.  B,  also  with  seven  individuals,  has  no  record  for 
the  first  regeneration;  the  second  is  9.1  mm.,  the  third  8.9,  the  fourth 
7.2  and  the  fifth  7.8.  C,  with  nineteen  individuals,  has  a  first  regen- 
eration average  of  8.6  mm.,  a  second  of  8.0,  a  third  of  7.5,  a  fourth  of 
5.5  and  a  fifth  of  6.4.  In  all  the  cases  there  is  a  decrease  in  the  amount 
regenerated  with  successive  removal  except  for  the  fifth  regeneration, 
which  has  in  each  case  an  increase  over  the  fourth.    It  is  probable  that 

TABLE  36 
Rana  clamitans      Series  3564-3624      Age  factor  not  eliminated 
Completed  successive  regenerations  compared 


Set 

Catalog 
number 

Number  of 
individ- 
uals 

First 
regenera- 
tion 
36  Days 

Second 
regenera- 
tion 
36  Days 

Third 
regenera- 
tion 
37  Days 

Fourth 
regenera- 
tion 
36  Days 

Fifth 
regenera- 
tion 
39  Days 

A 

3564 

to 
3570 

7 

•• 

9.8 

9.3 

8.5 

8.6 

B 

3578 

to 
3584 

7 

•■ 

9.1 

8.9 

7.2 

7.8 

C 

3586 

to 
3624 

19 

8.6 

8.0 

7.5 

5.5 

6.4 

57]  RATE    OF   REGEXERATION—ZELENY  57 

the  decrease  is  due  to  increase  in  age.  The  increase  from  the  fourth  tG 
the  fifth  regeneration  may  be  due  to  some  special  characteristic  of  the 
stage  immediately  preceding  metamorphosis  or  it  may  merely  indicate 
the  existence  of  some  uncontrolled  external  factor  such  as  food  or 
temperature. 

Discussion 

The  evidence  shows  clearly  that  when  the  age  factor  is  eliminated 
there  is  no  decrease  in  rate  of  regeneration  with  successive  removal. 
On  the  contrary  the  second  regeneration  is  more  rapid  than  the  first 
up  to  the  period  of  maximum  rate.  The  second  regeneration  however 
passes  its  maximum  sooner  than  does  the  first  and  after  the  tenth  day 
the  latter  therefore  catches  up  to  the  former  in  total  amount  regener- 
ated. There  is  no  striking  difference  between  the  second  and  the  third 
regenerations  but  in  each  comparison  the  third  has  a  slight  advantage. 

When  the  successive  regenerations  in  single  individuals  are  com- 
pared, the  rate  decreases  with  successive  removal.  This  decrease  is 
undoubtedly  due  to  the  age  factor. 

The  possibility  has  suggested  itself  that  the  second  regeneration 
starts  out  at  a  more  rapid  rate  than  the  first  because  the  cells  at  the 
cut  surface  were  undergoing  regenerative  changes  at  the  time  of  the 
new  operation  and  can  therefore  start  the  process  much  faster  than 
can  the  old  cells  at  the  first  surface  of  regeneration.  Following  a  first 
removal  there  is  a  considerable  degree  of  reorganization  of  the  cells 
at  the  cut  surface,  accompanied  by  active  migration.  During  this 
period,  which  in  Bana  clamitans  lasts  two  or  three  days,  there  is  little 
or  no  mitotic  cell  division.  Then  follows  a  division  period  which 
reaches  its  maximum  at  seven  to  ten  days.  Its  decline  is  associated 
with  the  oncoming  of  tissue  differentiation  (Sutherland  1915,  Metcalf 
1915). 

A  special  study  has  been  made  of  the  relative  rates  of  second 
regenerations  from  old  cells  following  a  cut  inside  of  the  first  removal 
level  and  from  new  cells  following  a  cut  outside  of  the  first  level.  This 
comparison  shows  only  a  very  slight  difference  in  favor  of  the  new 
cells  and  this  is  largely  confined  to  the  early  stages,  the  period  of  cell 
migration. 

The  period  of  increase  in  rate  is  the  period  of  active  cell  multipli- 
cation and  the  decline  in  rate  is  associated  with  cell  differentiation. 
The  second  regeneration  therefore  reaches  the  period  of  differentiation 
slightly  in  advance  of  the  first  regeneration. 

Apart  from  the  slowing  due  to  age  there  is  no  indication  of  a 
limitation  of  the  amount  of  new  material  that  may  be  produced  by 
regeneration.     The  actual  limitation  comes  not  from  the  using  up  of 


58  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [58 

regenerative  or  developmental  energy  or  of  determiners  by  repeated 
regeneration  but  from  changes  in  the  non-regenerating  part  associated 
with  age.  In  another  place  there  is  a  discussion  of  the  possibility  that 
there  may  be  an  effect  upon  the  rate  of  developmental  processes  in 
the  organism  as  a  whole  due  to  continued  regeneration  of  a  part.  This 
is  studied  particularly  in  connection  with  the  effect  of  regeneration 
upon  rate  of  metamorphosis  in  Amphibia. 

Regeneration  studies  in  general  and  those  on  successive  regener- 
ation in  particular  make  it  improbable  that  there  is  a  definite  number 
of  cell  generations  between  the  fertilized  egg  and  the  end  product,  the 
differentiated  cells.  The  possibility  that  certain  cells  may  remain  in 
an  early  cell  generation  can  not  be  wholly  excluded  as  an  explanation 
of  at  least  a  part  of  first  regeneration  phenomena.  Under  suitable  stimu- 
lation such  cells  may  be  postulated  to  take  up  development  where  it 
had  left  off.  The  definite  descriptions  of  de-differentiations  of  cells 
as  well  as  other  facts  of  regeneration  argue  against  this  conclusion. 
The  view  that  there  can  be  no  such  definite  number  of  cell  generations 
is  strengthened  by  the  facts  of  successive  regeneration.  It  does  not 
seem  probable  that  embryonic  cells  of  an  early  cell  generation  can  be 
held  in  reserve  through  repeated  regenerations. 

The  explanation  of  regeneration  by  the  theory  of  duplicate  sets  of 
determiners  meets  difficulties  in  undiminished  successive  regenerations. 
The  greater  the  number  of  repeated  regenerations  the  greater  the  diffi- 
culties of  explanation  on  this  basis.  Of  course  the  difficulty  does  not 
hold  for  the  hypothesis  that  every  cell  or  nearly  every  cell  contains  a 
full  set  of  determiners. 

The  earlier  appearance  of  the  maximum  rate  in  the  second  than 
in  the  first  regeneration  may  be  due  to  the  more  rapid  progress  of  the 
cells  in  the  early  cell  migration  period  alone  or  it  may  be  due  to  the 
acceleration  of  the  whole  developmental  cycle. 

Summary 

1.  The  age  factor  was  eliminated  in  Experiments  I  to  IV.  Ex- 
periments I  and  II  deal  with  tadpoles  of  Rana  clamitans  and  Experi- 
ments III  and  IV  with  larvae  of  Amblystoma  punctatum. 

2.  In  Experiment  I  approximately  one-half  of  the  tail  was  re- 
moved. At  six  days  the  average  first  regeneration  length  is  2.01  mm. 
and  the  average  second  regeneration  length  2.18  mm.  In  five  cases  the 
first  exceeds  the  second  and  in  six  the  second  exceeds  the  first.  The 
corresponding  specific  lengths  are  0.194  and  0.205.  The  first  regen- 
eration exceeds  the  second  in  two  sets,  the  second  exceeds  the  first  in 
eight  and  one  is  tied.  The  second  regeneration  has  the  advantage  in  all 
the  comparisons. 


59]  RATE    OF    REGENERATION— ZELENY  59 

3.  At  eight  days  in  Experiment  I  the  average  first  regeneration 
length  is  3.06  mm.,  and  the  second  3.42  mm.  The  first  exceeds  the  sec- 
ond in  three  sets  and  the  second  exceeds  the  first  in  seven.  The  corre- 
sponding average  specific  lengths  are  0.298  and  0.323.  In  four  sets 
the  first  regeneration  exceeds  the  second  and  in  six  the  second  exceeds 
the  first.  The  second  regeneration  has  the  advantage  in  all  the  com- 
parisons. 

4.  The  advantage  of  the  second  regeneration  over  the  first  in 
Experiment  I  holds  true  of  second  regenerations  from  both  old  tissue 
and  new  tissue  levels. 

5.  In  Experiment  II  observations  were  made  at  the  1/10,  1/3,  1/2 
and  2/3  levels  in  a  sufficient  number  of  individuals  to  yield  valid  data. 
^Regeneration  measurements  were  made  at  each  of  these  levels  4,  6,  8, 
10,  12^,  18  and  56  days  after  the  operations.  The  second  regen- 
eration at  all  of  them  tends  to  be  ahead  of  the  first  until  the  tenth  day, 
after  which  the  first  regeneration  catches  up.  The  maximum  rate  for 
both  regenerations  is  reached  before  this  time  and  earlier  for  the  second 
than  for  the  first  regeneration. 

6.  In  Experiment  III  two-thirds  of  the  tail  was  removed.  A 
comparison  of  the  first,  second  and  third  regenerations  was  made  at 
2,  4,  6,  8,  10  and  14  days..  At  two  days  the  first,  second  and  third 
regenerations  average  respectively  0.22,  0.25  and  0.26  mm.  The  cor- 
responding values  at  four  days  are  0.66,  0.75  and  1.00;  at  six  days 
1.36,  1.40  and  1.46;  at  eight  days  2.18,  2.68  and  2.68;  at  ten  days  3.55, 
3.82  and  4.20;  at  fourteen  days  5.34,  6.12  and  6.08.  The  advantage  is 
in  favor  of  the  second  and  third  regenerations  as  opposed  to  the  first 
and  of  the  third  as  opposed  to  the  second.  Individual  comparisons  at 
each  of  the  different  times  as  well  as  in  the  experiment  as  a  whole 
show  the  same  results. 

7.  The  removed  tails  in  the  preliminary  procedure  of  Experi- 
ment III  furnish  the  data  of  Experiment  IV  and  allow  a  comparison 
of  the  first  and  second  regenerations  at  eleven  days.  The  procedure  is 
however  subject  to  greater  error  than  that  of  Experiments  I  to  III. 
Twenty-five  individuals  for  each  regeneration  give  an  average  of  4.55 
±0.11  mm.  for  the  first  regeneration  and  4.50  40.10  mm.  for  the  second 
regeneration.  The  first  regeneration  is  ahead  of  the  second  in  ten 
cases,  the  second  ahead  of  the  first  in  twelve  cases  and  three  are  equal. 
The  two  regenerations  must  be  considered  as  essentially  equal. 

8.  In  Experiments  V  and  VI  the  age  factor  is  not  eliminated. 
Successive  regenerations  in  single  individuals  are  compared.  In  Ex- 
periment V  one-half  of  the  tail  in  Amblystoma  larvae  was  removed. 
In  Experiment  VI  60  per  cent  of  the  tail  of  toad  tadpoles  was  removed. 


60  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [60 

The  time  intervals  vary  somewhat  in  each  set  but  it  is  evident  in  both 
cases  that  there  is  a  decrease  in  rate  of  regeneration  from  the  first  to 
the  third  and  fourth  regenerations.  This  decrease  is  undoubtedly  due 
to  increase  in  age  and  not  to  successive  removal. 

9.  In  Experiment  VII  a  comparison  of  the  completeness  of  re- 
generation in  single  individuals  of  Rana  clamitans  shows  a  progressive 
decrease  in  amount  regenerated  from  the  first  to  the  fourth  regener- 
ation and  an  increase  from  the  fourth  to  the  fifth.  In  this  experiment 
also  the  age  factor  is  not  eliminated  and  the  decrease  is  probably  due 
to  increase  in  age. 


61]  RATE    OF    REGENERATION— ZELENY  61 


PART  III 

THE  EFFECT  OF  LEVEL  OF  THE  CUT  UPON  THE  RATE  AND 
COMPLETENESS  OF  REGENERATION 

The  present  study  gives  a  description  of  some  experiments  made  to 
define  more  accurately  than  has  been  done  the  exact  relation  between 
the  level  of  the  cut  and  rate  of  regeneration  and  especially  the  relation 
of  this  factor  to  the  other  factors  affecting  rate  and  completeness  of 
regeneration.  The  factor  is  one  of  great  interest  because  if  it  is  true  that 
the  ratio  between  length  regenerated  per  unit  time  and  length  removed 
is  a  constant  it  follows  that  no  matter  how  much  material  is  removed 
regeneration  is  always  completed  in  the  same  time.  It  is  therefore  of 
great  interest  to  determine  the  extent  to  which  this  statement  is  true, 
to  analyze  the  elements  of  the  level  factor  and  to  determine  its  relation 
to  other  factors. 

Experiment  I  Rana  clamitans  Series  3676-3765 
The  tadpoles  were  collected  on  December  9,  1911,  and  first  removals 
were  made  in  two-thirds  of  the  individuals  on  December  22.  A  second 
removal  was  made  in  these  individuals  on  January  8,  and  at  the  same 
time  a  first  removal  in  the  other  one-third.  Measurements  were  made 
four,  six,  eight,  ten,  twelve  and  a  half,  eighteen  and  fifty-six  days  after 
the  operations  of  January  8.  The  first  and  second  regenerations  are 
treated  separately  and  the  second  regenerations  are  taken  up  first  because 
they  have  a  larger  number  of  individuals  and  therefore  give  the  more 
uniform  results. 

Second  Regenerations 

The  different  amounts  removed  approximate  6,  10,  18,  31,  49  and  67 
per  cent  of  the  tail  length.  There  are  four  individuals  at  the  lowest 
removal,  averaging  1.5  mm.,  seven  at  the  next,  averaging  2.8  mm.,  five 
at  the  third  with  an  average  of  4.9  mm.,  ten  at  the  fourth  with  8.4  mm., 
eight  at  the  fifth  with  13.1  mm.,  and  ten  at  the  sixth  with  18.1  mm.  The 
data  are  given  in  tables  37  to  40  and  in  graphic  form  in  figures  4  to  17. 

The  regenerated  lengths  at  ten  days  will  be  taken  up  first  because 
at  this  time  the  period  of  maximum  rate  has  been  passed  and  its  full 
effect  is  represented.    Differentiation  of  the  tissues  has  begun  but  there 


62  ILLINOIS    BIOLOGICAL    MONOGRAPHS  [62 

is  still  a  considerable  production  of  new  cells  by  mitotic  division  except  in 
the  individuals  with  the  two  shortest  removals  in  which  the  process  is 
completed.  The  regenerated  lengths  for  the  six  levels  beginning  with  the 
shortest  removal  are  respectively  1.0,  1.3,  1.4,  2.3,  3.7  and  5.1  mm.  The 
data  are  given  in  the  last  two  columns  of  table  37.  There  is  very  dis- 
tinctly an  increase  in  regenerated  length  with  increase  in  removed 
length.  Dividing  the  regenerated  length  by  the  removed  length  at  each 
level,  the  fractions  obtained  are 

1.0        1.3        1.4        2.3        3.7  5.1 

»  .  .  ,  ,  and        , 

1.5        2.8        4.9        8.4      13.1  18.1 

which  give  the  specific  regenerated  lengths  or  lengths  regenerated  per 
unit  of  removed  lengths.  These  values  are  0.67,  0.46,  0.29,  0.28,  0.28  and 
0.28.  They  show  a  remarkable  constancy  for  removed  lengths  of  4.9 
mm.  and  over.  The  relations  between  removed  lengths  and  regenerated 
lengths  are  further  shown  in  figure  4  which  gives  the  removed  lengths 
along  the  horizontal  axis  and  the  regenerated  lengths  parallel  to  the 
vertical  axis.  The  plotted  line  of  correlation  between  the  two  values 
is  straight  except  for  the  two  lowest  removed  lengths.  The  specific 
lengths  are  given  in  Figure  5  in  which  the  removal  lengths  again  are 
along  the  horizontal  axis  and  the  lengths  regenerated  per  unit  of  removed 
length  parallel  to  the  vertical  axis.  The  line  of  correlation  is  straight 
and  parallel  to  the  horizontal  axis  for  the  four  highest  removals.  For 
these  therefore  the  regenerated  length  is  directly  proportional  to  the 
removed  length  or  in  other  words  within  these  limits  the  same  percent- 
age of  the  removed  length  is  regenerated  in  each  within  the  given  time 
of  ten  days. 

The  two  lowest  removed  lengths  give  a  higher  specific  rate  than  the 
others.  They  regenerate  a  higher  percentage  of  the  removed  length 
within  the  given  time. 

The  ten  day  period  is  chosen  as  the  first  example  because  it  is  the 
first  one  to  receive  the  full  benefit  of  the  periods  of  maximum  rate  of 
regeneration,  the  periods  during  which  rapid  multiplication  of  cells 
takes  place.  The  other  periods  give  results  which  agree  in  general 
features  after  the  first  few  days  with  those  at  ten  days  but  depart  from 
them  in  certain  respects. 

The  remaining  periods  will  now  be  taken  up  in  turn  beginning  with 
the  shortest. 

During  the  first  four  days  after  the  operation  the  rate  of  regenera- 
tion is  slow,  the  new  tissue  being  derived  largely  from  migration  of 
cells  over  the  cut  surface.  Measurements  of  regeneration  at  this  time 
are  especially  subject  to  error  because  of  the  small  amount  regenerated 


63] 


RATE    OF    REGENERATION— ZELENY 


63 


and  because  of  irregularity  in  the  outer  edge  of  the  regenerating  tissue. 
The  regenerated  lengths  at  four  days  are  respectively  0.22,  0.39,  0.24, 
0.42,  0.50  and  0.52  mm.    These  data  are  given  in  table  37  and  are  rep- 


mm 

5.0 

-d 

40 

O) 

+j 

a 

u 

o> 

3.0 

O) 

M) 

4> 

t* 

m 

2.0 

X) 

tt 

c 

1.0 


1.5    2.8         4.9  8.4  13.1 

— >■      Lengths  removed  in  mm. 
Figure  4  Rana  clamitans    Second  regenerations    Ten  days 


18.1 


bo 
a 

- 

o 

<a 

•** 
o 

- 

02 


mm. 
0.60 
0.50 
0.40 
0.30 
0.20 
0.10 


Figure  5 


1.5 


13.1 


2.8         4.9  8.4 

— >■      Lengths  removed  in  mm. 
Rana  clamitans    Second  regenerations    Specific  lengths 


18.1 


Ten  days 


resented  graphically  in  figure  6.  Dividing  the  regenerated  lengths  by 
the  removed  lengths  the  fractions  obtained  are 

0.22        0.39        0.24        0.42        0.50  0.52 

L50        2~!80        4~!90        8A~6      1310  1810 

giving  specific  lengths  of  0.15,  0.14,  0.05,  0.05,  0.04  and  0.03.  These 
relations  are  represented  graphically  in  figure  7.  There  is  on  the  whole 
a  slight  increase  in  regenerated  length  with  increase  in  removed  length 
but  this  increase  is  not  proportional  to  the  amount  removed  so  that  the 
proportion  regenerated  decreases  with  increase  in  removed  length.    The 


64 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[64 


approach  to  equality  in  regeneration  at  this  time  is  probably  due  to 
the  fact  that  the  new  tissue  is  largely  made  up  of  migrating  cells  and 
there  is  not  a  striking  difference  in  the  extent  of  the  migration  at  the 
different  levels. 

The  specific  length  of  material  regenerated  after  the  smallest 
removals  is  greater  than  that  regenerated  after  the  larger  removals  not 
only  at  four  days  but  also  later.  It  is  probable  that  the  factors  involved 
during  the  first  few  days  of  regeneration  are  quite  different  from  those 
during  later  days.  Following  the  injury  there  is  a  disintegration  of 
injured  cells  associated  with  an  active  migration  of  the  epidermal  cells 


00 

a 
a> 


1.0 


Figure  6 


1.5    2.8         4.9  8.4  13.1 

— ►      Lengths  removed  in  mm. 
Rana  clamitans     Second  regenerations    Four  days 


18.1 


"8 

bfi 

a 


A3 

8 


0.20 
0.10 


13.1 


18.1 


o,  Figure  7 

CO 


1.5    2.8  4.9  8.4 

— >-      Lengths  removed  in  mm. 
Rana  clamitans    Second  regenerations     Specific  lengths     Four  days 


over  the  cut  surface.  There  is  practically  no  mitotic  cell  division.  The 
rapid  multiplication  of  cells  comes  later.  These  processes  of  cell  migra- 
tion apparently  are  not  essentially  different  at  the  different  levels.  They 
are  local  responses  of  the  cells  at  the  cut  surface.  With  the  appearance 
of  rapid  cell  multiplication  there  is  a  marked  difference  at  different 
levels  though  the  shortest  removals  still  show  a  greater  specific  length 
than  the  others  probably  because  in  their  ease  the  migrated  cells  make 
up  a  large  percent  of  the  total  material  of  the  new  part. 

Between  the  end  of  the  fourth  and  the  end  of  the  sixth  day  after 
the  operation  mitotic  cell  division  becomes  very  rapid  and  the  rate  of 
regeneration  for  second  regenerations  reaches  its  maximum  at  a  majority 
of  the  levels  on  the  sixth  day.  At  six  days  the  regeneration  for  the  six 
levels  is  respectively  0.62,  0.80,  0.70,  1.1,  1.7  and  2.3  mm.,  as  shown  in 


65] 


RATE    OF   REGENERATION— ZELENY 


65 


Table  37.  A  graphic  representation  is  given  in  Figure  8.  There  is  a  grad- 
ual increase  with  increase  in  removed  length.  The  fractions  obtained  by 
dividing  by  the  removed  lengths  are : 

0.62        0.80        0.70        1.1        1.7  2.3 

,  ,  ,  ,  ,  and  

1.5  2.8  4.9  8.4      13.1  18.1 

They  give  specific  lengths  of  0.42,  0.30,  0.14,  0.13,  0.13  and  0.13.  The 
smaller  removals  still  have  the  larger  specific  lengths  but  with  removals 
of  4.9  mm.  and  more  there  is  an  approach  to  constancy.  The  relations 
are  shown  graphically  in  Figure  9. 

Tj    mm. 


to 

a 

<D 


2.0 


1.0 


Figure  8 


1.5    2.8         4.9  8.4  13.1 

— ►      Lengths  removed  in  mm. 
Ram  clamitans    Second  regenerations     Six  days 


18.1 


1 

a 


0.40 
0.30 
0.20 
0.10 


Figure  9 


1.5    2.8        4.9  8.4 

— >■      Lengths  removed  in  mm. 
Rana  clamitans     Second  regenerations 


13.1 


18.1 


Specific  lengths     Six  days 


The  rate  of  regeneration  between  the  sixth  and  the  eighth  day  for 
second  regenerations  is  not  quite  as  high  as  for  the  preceding  period, 
but  mitotic  divisions  are  still  very  numerous  and  differentiation  of  the 
cells  is  just  beginning.  At  eight  days  the  regenerated  lengths  are 
respectively  0.9,  1.1,  1.2,  1.8,  2.7  and  3.7  mm.  as  shown  in  table  37. 
The  increase  in  regeneration  with  increase  in  removed  length  is  evident. 
The  relations  are  shown  in  Figure  10.  Dividing  by  the  removed  lengths 
the  fractions  obtained  are 

0.9        1.1        1.2        1.8        2.7  3.7 


1.5        2.8 


4.9 


8.4      13.1 


and 


18.1 


66 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[66 


giving  the  specific  regenerations  0.60,  0.39,  0.24,  0.22,  0.21,  0.20.  There 
is  a  graphic  representation  in  Figure  11.  As  before,  the  two  shortest 
removals  give  the  highest  specific  rates  but  beyond  these  there  is  an 
approach  to  constancy  though  there  is  still  a  slight  decrease  with  increase 
in  removal. 

The  ten  day  values  have  already  been  given. 

Between  ten  and  twelve  and  a  half  days  after  the  operation  there 
is  no  further  growth  in  the  case  of  the  two  shortest  removals.  In  the 
two  medium  removals  the  process  is  completed  at  twelve  and  a  half 
days.     In  the  two  longest  removals  there  is  still  a  small  amount  of 


mm. 
4.0 

3.0 

2.0 


to     10 

c 
e 


Figure  10 


1.5    2.8  4.9  8.4  13.1 

— '—>■      Lengths  removed  in  mm. 
Rana  clamitans    Second  regenerations    Eight  days 


18.1 


- 


0.60 
0.50 
0.40 
0.30 
0.20 
0.10 


Figure  11 


13.1 


18.1 


1.5    2.8         4.9  8.4 

— >■      Lengths  removed  in  mm. 

Rana  clamitans  Second  regenerations    Specific  lengths    Eight  days 


proliferation  after  this  time.  At  twelve  and  a  half  days  the  regenerated 
lengths  are  1.0,  1.3,  1.6,  2.6,  4.4  and  6.2  mm.  as  shown  in  Table  38.  The 
increase  with  increase  in  removed  length  is  continuous.     This  is  shown 


67] 


RATE    OF   REGENERATION— ZELENY 


67 


Dividing  by  the  removed  lengths  the 


in  graphic  form  in  figure  12. 
fractions  obtained  are 

1.0        1.3        1.6        2.6        4.4  6.2 

»         ,         ,         ,  and          

1.5        2.8        4.9        8.4  13.1  18.1 

giving  specific  lengths  of  0.67,  0.46,  0.33,  0.31,  0.34  and  0.34. 


graph  for  specific  lengths  is  shown  in  figure  13. 


The 
There  is  still  a  fair 


§ 

0 


mm. 

6.0 

5.0 
4.0 
3.0 

2.0 
1.0 


Figure  12 

-  mm. 

I  0.70 

fe  0.60 

|  0.50 

C  0.40 

|  0.30 

bo 

S  0.20 

B 

~  0.10 


Figure  13 


1.5    2.8  4.9  8.4 

— >-      Lengths  removed  in  mm. 
Rana  clamitans      Second  regenerations 


13.1 


18.1 


Twelve  and  a  half  days 


1.5    2.8         4.9  8.4 

— y      Lengths  removed  In  mm. 
Rana  clamitans    Second  regenerations 


13.1 


18.1 


Specific  lengths      Twelve 


and  a  half  days 


approach  to  constancy  with  removals  of  4.9  mm.  and  above.  The  rela- 
tive increase  in  the  case  of  the  higher  removals  is  due  to  the  fact  that 
regeneration  is  continuing  in  them  after  it  has  stopped  in  the  others. 


68 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[68 


Therefore  the  data  after  this  time  are  values  for  the  completeness  of 
regeneration  rather  than  for  the  rate. 

Between  twelve  and  a  half  and  eighteen  days  after  the  operation 
there  is  no  further  regeneration  in  the  tails  with  the  four  shortest  re- 
movals. Two  of  them  even  exhibit  a  decrease  in  size.  The  two  longest 
removals  show  only  a  slight  increase.  At  eighteen  days  the  regenerated 
lengths  are  respectively  1.0,  1.2,  1.5,  2.6,  4.8  and  7.0  mm.  as  given  in 
Table  38.  The  same  data  are  represented  in  graphic  form  in  Figure  14. 
Dividing  by  the  removed  lengths  the  fractions  obtained  are 
1.0        1.2        1.5        2.6        4.8  7.0 

»  •  .  1  »  and  

1.5        2.8        4.9        8.4      13.1  18.1 

giving  specific  lengths  of  0.67,  0.43,  0.31,  0.31,  0.37  and  0.39.  The  graph  is 
shown  in  Figure  15. 


bo 
c 


7.0 


6.0 


■g     5.0 


4.0 


3.0 


2.0 


1.0 


Figure  14 


1.5    2.8  4.9  8.4  13.1 

— >■      Lengths  removed  in  mm. 
Rana  clamitans       Second  regenerations      Eighteen  days 


18.1 


At  eighteen  days  there  is  very  little  regeneration  at  any  of  the 
levels  and  at  some  of  them,  especially  the  shorter  removals,  a  consider- 
able absorption  of  regenerated  material.  Regeneration  may  therefore 
be  considered  as  completed  at  this  time.  However  the  measurements  for 
56  days  are  given  in  order  to  show  the  changes.  The  regenerated 
lengths  at  that  time  are  0.9,  0.7,  1.6,  2.5,  5.2  and  7.1  mm.    These  data 


69] 


RATE    OF    REGENERATION— ZELENY 


69 


— 

2 

E 

mm. 
0.70 

E 

0.60 
0.50 

m 

bo 

a 

0.40 
0.30 
0.20 

o 

2 
o 

0.10 

Fig 

ure  15 

een  days 

1.5    2.8  4.9  8.4 

— ►■      Lengths  removed  in  mm. 

Ram  clamitans     Second  regenerations 


13.1 


18.1 


Specific  lengths     Eight- 


are  given  in  table  38  and  are  represented  in  graphic  form  in  figure  16. 
Dividing  by  the  average  removed  lengths,  which  differ  somewhat  from 
the  previous  ones  because  of  the  death  of  certain  individuals,  the  frac- 
tions obtained  are 

0.9        0.7        1.6        2.5        5.2  7.1 


1 

2 

■ 
j 

0/ 


o> 


3.0 


2.0 


1.0 


1.5 


2.6 


4.9 


8.2      13.2 


and 


17.9 


mm. 
7.0 

6.0 
5.0 
4.0 


Figure  16 


1.5    2.6  4.9  8.2  13.2 

— >■      Lengths  removed  in  mm. 
Ram  clamitans       Second  regenerations      Fifty-six  days 


17.9 


70 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[70 


giving  specific  regenerations  of  0.60,  0.27,  0.33,  0.31,  0.39  and  0.40.  These 
are  shown  in  the  graph  given  in  figure  17.  Because  of  the  absorption 
of  regenerated  tissue  in  the  shorter  removals  and  a  slight  growth  in  the 
longer  ones  the  latter  show  a  comparative  increase  in  specific  lengths. 


0.60 

i 

0.50 

<0 

t- 

040 

0.30 

bl) 

a 

© 

0.20 

o 

0.10 

o 

0) 

a 

GO 

1.6       2.6  4.9  8.2 

— >■      Lengths  removed  in  mm. 


13.2 


17.9 


Figure  17      '  Rana  clamitans      Second  regenerations      Specific  lengths      Fifty- 
six  days 


For  a  comparison  of  completeness  of  regeneration  it  is  better  to 
take  the  greatest  lengths  regenerated  at  each  level  rather  than  the 
amounts  regenerated  at  any  particular  time  because  the  shorter  levels 
complete  regeneration  and  begin  to  absorb  the  tissues  sooner  than  do 
the  longer  ones.  On  this  basis  the  greatest  regenerated  lengths  at  each 
of  the  six  levels  are,  for  the  1.5  mm.  level  1.0  mm.  reached  at  ten  days, 
for  the  2.8  level  1.3  mm.  reached  at  ten  days,  for  the  4.9  level  1.6  mm. 
reached  at  twelve  and  a.  half  days,  for  the  8.4  level  2.6  mm.  reached  at 
twelve  and  a  half  days,  for  the  13.2  level  5.2  mm.  reached  at  fifty-six 
days,  and  for  the  17.9  level  7.1  mm.  reached  at  fifty-six  days.  These 
data  are  given  in  tables  37,  38,  39  and  40  and  in  graphic  form  in  figure 
18.  At  the  last  two  levels  there  was  a  slight  increase  from  eighteen 
to  fifty-six  days  but  this  almost  certainly  came  during  the  early  part 
of  the  period  and  the  values  are  therefore  completed  values.  Dividing 
by  the  removed  lengths  the  fractions  obtained  are 


1.0 

1.3 

1.6 

2.6 

5.2 

1.5 

2.8 

4.9 

8.4 

13.2 

and 


7.1 
i7~9 


giving  specific  lengths  of  0.67,  0.46,  0.33,  0.31,  0.39  and  0.40.  The  graph 
is  given  in  Figure  19.  The  high  values  for  the  two  short  levels  are 
probably  due  to  the  fact  that  the  cells  migrating  to  the  cut  surface  form 


71] 


RATE    OF   REGEXERATIOX —ZELENY 


71 


7.0 


6.0 


©     5.0 

a 

E 
■ 

§     4.0 

M 


f 


3.0 


2.0 


1.0 


Figure  18 

mm. 
0.70 

■ 

d 
I 
■ 
8 

0.60 
0.50 

IB 

3 

■«-> 

H 

0.40 
0.30 

.2 

0.20 

Q 

2 

o 

B 
D. 
02 

0.10 

ni:". 

Figure  19 

ness 

1.5    2.8  4.9  8.4 

— >-      Lengths  removed  in  mm. 
Rana  clamitans    Second  regenerations 


13.2 


Completeness 


17.9 


1.5    2.8         4.9  8.4 

— >■      Lengths  removed  in  mm. 
Rana  clamitans    Second  regenerations 


13.2  17.9 

Specific  lengths    Complete- 


a  large  proportion  of  the  total  mass  of  the  regenerated  organ.  Since 
apparently  the  length  of  this  mass  of  cells  is  very  much  alike  at  all 
levels  as  indicated  by  the  facts  of  the  four  day  regenerations,  the  specific 
lengths  for  these  short  removals  are  greater  than  for  the  others.  The 
high  values  of  the  two  longest  removals  are  due  to  a  continuation  of 


72 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[72 


regeneration  at  these  levels  after  it  has  ceased  at  the  others.  At  ten 
days  the  specific  lengths  regenerated  are  very  nearly  the  same  at  all  the 
levels  except  the  first  two. 


Rana  clamitans 


TABLE  37 
Series  3676-3765 


Second  regenerations 


Catalog 
number 

Removed 
length 

in 
mm. 

4   Days 

6   Days 

8  Days 

10  Days 

Percent 
removed 
Average 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

3676 

1.3 

0.27 

0.60 

0.9 

1.0 

3682 

1.6 

0.18 

0.60 

0.9 

1.0 

3730 

1.6 

0.39 

0.75 

0.9 

0.9 

6 

3754 

1.6 

0.06 

0.55 

0.9 

1.1 

Average 

1.5 

0.22 

0.15 

0.62 

0.42 

0.9 

0.60 

1.0 

0.67 

3677 

2.0 

0.30 

0.6 

0.9 

0.9 

3696 

2.1 

0.48 

0.8 

1.0 

1.1 

3701 

3.2 

0.42 

0.8 

1.1 

1.2 

3713 

2.8 

0.36 

0.8 

0.9 

0.9 

10 

3719 

3.1 

0.30 

0.8 

1.1 

1.4 

3749 

2.8 

0.48 

0.6 

1.2 

1.4 

3750 

3.5 

0.42 
0.39 

1.3 

0.30 

1.7 

1.1 

1.9 
1.3 

Average 

2.8 

0.14 

0.80 

0.39 

0.46 

3678 

5.0 

0.20 

0.5 

0.9 

1.0 

3684 

5.5 

0.15 

0.7 

1.2 

1.4 

3702 

4.7 

0.42 

0.8 

1.1 

1.3 

18 

3720 

4.6 

0.06 

0.3 

1.3 

1.8 

3756 

4.8 

0.36 
0.24 

1.0 

1.3 
1.2 

1.7 

1.4 

Average 

4.9 

0.05 

0.70 

0.14 

0.24 

0.29 

1 

' 

73] 


RATE    OF   REGENERATION— ZELENY 


73 


Rana  clamitans 


TABLE  37  (Continued) 
Series  3676-3765  Second  regenerations 


Catalog 
number 

Removed 
length 

in 
mm. 

4   Days 

6   Days 

8  Days 

10  Days 

Percent 
removed 
Average 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen • 

erated 

length 

mm. 

1.4 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

3679 

8.4 

0.30 

0.7 

1.9 

3685 

9.3 

0.60 

1.2 

1.9 

2.3 

3697 

7.3 

0.48 

1.2 

1.7 

2.2 

3703 

9.3 

0.45 

1.3 

2.0 

2.5 

3715 

7.9 

0.24 

0.9 

1.7 

2.3 

31 

3721 

8.7 

0.57 

1.3 

1.9 

2.3 

3733 

8.5 

0.36 

1.0 

1.9 

2.4 

3739 

9.6 

0.36 

1.0 

1.8 

2.4 

3751 

6.7 

0.45 

1.1 

1.7 

2.1 

3757 

8.0 

0.42 

1.2 

2.1 

2.8 

Average 

8.4 

0.42 

0.05 

1.1 

0.13 

1.8 

.  0.22 

2.3 

0.28 

3686 

14.5 

0.60 

2.1 

3.4 

4.8 

3698 

14.9 

0.50 

1.5 

3.3 

4.3 

3704 

14.5 

0.45 

2.2 

3.3 

4.4 

3716 

12.7 

0.39 

1.7 

2.4 

3.4 

3722 

12.5 

0.60 

1.6 

2.6 

3.6 

49 

3740 

13.9 

0.30 

1.1 

2.1 

3.0 

3752 

11.2 

0.54 

1.7 

2.5 

3.4 

3758 

11.0 

0.60 

1.5 

2.2 

0.21 

2.9 

Average 

13.1 

0.50 

0.04 

1.7 

0.13 

2.7 

3.7 

0.28 

3680 

16.0 

0.60 

1.9 

3.0 

4.2 

3681 

21.2 

0.84 

3.0 

4.0 

5.6 

3687 

19.7 

0.54 

3.6 

5.6 

6.0 

3699 

21.0 

0.54 

2.2 

4.3 

5.9 

3705 

17.6 

0.72 

2.0 

3.6 

4.8 

3717 

17.6 

0.42 

2.6 

3.6 

5.2 

67 

3723 

18.4 

0.30 

2.3 

3.7 

5.3 

3735 

16.5 

0.48 

2.0 

3.4 

5.5 

3741 

16.0 

0.30 

1.9 

3.0 

5.4 

3753 

16.8 

0.42 

0.03 

2.0 

2.5 

3.8 

Average 

18.1 

0.52 

2.3 

0.13 

3.7 

0.20 

5.1 

0.28 

74 


ILLIXOIS    BIOLOGICAL    MONOGRAPHS 


[74 


Rana  clamitans 


TABLE  38 

Series  3676-3765 


Second  regenerations 


Catalog 
number 

Removed 
length 

in 
mm. 

12 J   Days 

18   Days 

56  Days 

Highest  values 

Percent 
removed 
Average 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

3676 

1.3 

1.0 

1.0 

0.7 

1.0 

3682 

1.6 

1.0 

1.0 

1.1 

1.1 

3730 

1.6 

0.9 

0.9 

0.7 

0.9 

6 

3754 

1.6 

1.2 

0.67 

1.2 

1.1 

1.2 
1.0 

Average 

1.5 

1.0 

1.0 

0.67 

0.9 

0.60 

0.67 

3677 

2.0 

0.9 

0.9 

0.7 

0.9 

3696 

2.1 

1.0 

1.0 

0.7 

1.1 

3701 

3.2 

0.9 

0.9 

0.5 

1.2 

3713 

2.8 

1.4 

1.3 

1.4 

10 

3719 
3749 

3.1 

2.8 

1.4 
2.0 

1.3 

2.0 

0.9 

1.4 

2.0 

3750 

3.5 

1.3 

1.3 

0.7 

1.9 
1.3 

Average 

2.8 

1.3 

0.46 

1.2 

0.43 

0.27 

0.46 

3678 

.5.0 

1.1 

1.1 

1.1 

3684 

5.5 

1.4 

1.5 

1.4 

1.5 

3702 

4.7 

1.3 

1.3 

1.3 

1.3 

18 

3720 

4.6 

2.3 

1.9 

2.0 

2.3 

3756 

4.8 

1.8 

1.6 

1.6 

1.8 

Average 

4.9 

1.6 

0.33 

1.5 

0.31 

0.33 

1.6 

0.33 

3679 

8.4 

1.9 

2.1 

2.1 

3685 

9.3 

2.8 

3.0 

2.6 

3.0 

3697 

7.3 

2.4 

2.3 

2.1 

2.4 

3703 

9.3 

2.6 

2.5 

2.5 

2.5 

3715 

7.9 

2.6 

2.6 

2.8 

2.8 

3721 

8.7 

2.6 

2.3 

2.2 

2.6 

31 

3733 
3739 

8.5 
9.6 

2.6 
3.0 

2.6 
2.9 

2.8 

2.8 
3.0 

3751 

6.7 

2.4 

2.5 

2.3 

2.5 

3757 

8.0 

3.1 

3.2 

3.1 
2.5 

3.2 
2.6 

Average 

8.4 

2.6 

0.31 

2.6 

0-31 

0.31 

0.31 

75] 


RATE    OF    REGENERATION— ZELENY 
TABLE  38  (Continued) 


75 


Catalog 
number 

Removed 
length 

in 
mm. 

12* 

Days 

18 

Days 

56  Days 

Highest  values 

Percent 
removed 
Average 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

3686 

14.5 

5.3 

5.2 

5.3 

3698 

14.9 

5.0 

5.4 

5.4 

5.4 

3704 

14.5 

5.2 

5.5 

5.4 

5.5 

3716 

12.7 

4.2 

5.1 

4.4 

5.1 

3722 

12.5 

3.9 

3.5 

4.2 

4.2 

49 

3740 
3752 

13.9 
11.2 

4.6 
4.1 

5.6 
4.0 

6.8 

6.8 
4.1 

3758 

11.0 

3.6 
4.4 

4.1 

4.9 
5.2 

4.9 
5.2 

Average 

13.1 

0.34 

4.8 

0.37 

0.39 

0.39 

3680 

16.0 

5.2 

6.4 

6.6 

6.6 

3681 

21.2 

6.3 

7.3 

7.2 

7.3 

3687 

19.7 

6.6 

7.0 

7.0 

3699 

21.0 

7.1 

7.5 

7.2 

7.5 

3705 

17.6 

6.4 

6.2 

6.0 

6.4 

67 

3717 

17.6 

6.0 

6.7 

6.4 

6.7 

3723 

18.4 

6.5 

8.1 

8.3 

8.3 

3735 

16.5 

6.5 

7.8 

8.0 

8.0 

3741 

16.0 

5.8 

6.9 

7.0 

7.0 

3753 

16.8 

5.2 

6.4 

7.1 
7.1 

7.1 
7.1 

Average 

18.1 

6.2 

0.34 

7.0 

0-39 

0.40 

0.40 

TABLE  39 

Rana  clamitans       Series  3676-3765       Summary      Second  regenerations 

Lengths  regenerated  at  different  levels  at  different  times 


Percent    of 

tail  length 

removed 

Length 
removed 
in  mm. 

Number 
of  indi- 
viduals 

Days  after  operation 

4 

6 

8 

10 

12/* 

18 

56 

6 

1.5 

4 

0.22 

0.6 

0.9 

1.0 
1.3 
1.4 
2.3 

1.0 

1.0 

0.9 

10 

2.8 

7 

0.39 

0.8 

1.1 

1.3 

1.2 

0.7 

18 

4.9 

5 

0.24 

0.7 

1.1 

1.2 

1.6 

1.5 

1.6 

31 

8.4 

10 

0.42 

1.8 

2.6 

2.6 

2.5 

49 

13.1 

8 

0.50 

1.7 

2.7 
3.7 

3.7 

5.1 

4.4 
6.2 

4.8 

5.2 

67 

1*.1 

10 

0.52 

2.3 

7.0 

7.1 

76 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[76 


TABLE  40 

Rana  clamitans     .Series  3676-3765      Summary      Second  regenerations 

Lengths  regenerated  at  different  levels  at  different  times 


Percent  of 

tail  length 

removed 

I      Length 
removed 
in  mm. 

Number 
of  indi- 
viduals 

Days  after  operation 

4 

6 

8 

10 

12!/2 

18 

56 

6 

1.5 

4 

0.15 

0.42 

0.60 

0.67 

0.67 

0.67 

0.60 

10 

2.8 

7 

0.14 

0.30 

0.39 

0.46 

0.46 

0-43 

0.27 

18 

4.9 

5 

0.05 

0.14 

0.24 

0.29 

0.33 

0.31 

0.33 

31 

8.4 

10 

0.05 

0.13 

0.22 

0.28 

0.31 
0.34 

0-31 

0.31 

49 

13.1 

8 

0.04 

0.13 

0.21 

0.28 

0-37 

0.39 

67 

18.1 

10 

0.03 

0.13 

0.20 

0.28 

0.34 

0.39 

0.40 

First  Regenerations 

The  data  for  first  regenerations  are  from  a  different  set  of  indi- 
viduals than  those  for  second  regenerations.  The  two  kinds  of  opera- 
tions were  made  on  the  same  day.  The  general  results  obtained  from  the 
first  regenerations  are  in  full  agreement  with  those  obtained  from  the 
second  regenerations  but  there  is  greater  variability  because  of  the 
smaller  number  of  individuals.  The  average  per  cents  of  the  tail  length 
removed  are  respectively  6,  10,  17,  30,  48  and  62  for  the  six  levels. 
The  first  of  these  has  two  individuals  averaging  1.5  mm.  of  removed 
tail,  the  second  five  individuals  with  an  average  of  2.6  mm.,  the  third 
three  individuals  with  an  average  of  4.6,  the  fourth  eight  with  an  average 
of  8.2,  the  fifth  five  with  an  average  of  13.0  and  the  sixth  five  with  an 
average  of  16.7.  The  data  for  these  experiments  are  given  in  Tables 
41,  42,  43  and  44  and  in  Figures  20  to  35. 

The  progress  of  a  first  regeneration  is  similar  to  that  of  a  second 
except  that  the  maximum  is  reached  later  in  the  case  of  first  regenera- 
tions. In  the  present  series  the  maximum  specific  rate  for  first  regenera- 
tions comes  between  the  sixth  and  the  eighth  day  after  the  operation. 
A  comparison  of  the  two  regenerations  is  made  in  the  section  on  the 
effect  of  successive  removal.  The  change  in  rate  during  the  process  of 
regeneration  is  also  discussed  in  a  separate  section. 


77] 


RATE    OF    REGENERATION— ZELENY 


77 


The  lengths  regenerated  during  the  first  four  days  are  respectively 
0.27,  0.15,  0.51,  0.45,  0.46  and  0.51  for  the  six  levels.  There  is  no 
regular  increase  with  removed  length.  The  data  are  given  in  Table  41 
and  in  Figure  20.  The  specific  lengths  regenerated  are  0.17,  0.06,  0.11, 
0.05,  0.03  and  0.03.  They  are  shown  in  Table  41  and  in  Figure  21.  As  in 
the  case  of  the  second  regeneration  the  shortest  removals  have  the 
largest  proportional  amounts.    This  first  period  being  the  period  of  cell 


1.0 


Figure  20 


1.5 


13.0 


2.6        4.6  8.2 

— y      Lengths  removed  in  mm. 
Rana  clamitans    First  regenerations    Four  days 


16.7 


migration  with  very  little  cell  division  it  is  probable  that  the  length  of 
the  material  furnished  in  this  way,  as  measured  along  the  main  axis  of 
the  individual,  is  independent  of  the  level  of  the  cut.  The  area  of  the  cut 
surface  of  course  is  greater  at  the  more  proximal  than  at  the  more  distal 
levels  so  that  the  actual  total  mass  of  regenerated  material  is  greater  at 
the  deeper  levels. 

At  six  days  the  rate  of  first  regenerations  is  rapidly  increasing, 
the  maximum  rate  coming  between  six  and  eight  days.  The  lengths 
regenerated  at  six  days  are  respectively  0.47,  0.5, 1.0, 1.1,  1.6  and  1.6  mm. 


mm. 
0.20 
0.10 


13.0 


16.7 


1.5    2.6        4.6  8.2 

— >■      Lengths  removed  in  mm. 
Figure  21     Rana  clamitans      First  regenerations     Specific  lengths     Four  days 


0Q 


78 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[78 


They  are  shown  in  Table  41  and  in  Figure  22.  There  is  in  general  an 
increase  with  increase  in  removed  length  but  the  first  is  not  proportional 
to  the  second.  The  specific  lengths  are  0.30,  0.18,  0.22,  0.13,  0.12  and 
0.09  as  shown  in  Table  41  and  Figure  23.  The  shorter  removals  still  have 
proportionately  the  greater  regenerations. 

•g    mm. 
«     2.0 


1.0 


1.5    2.6        4.6  8.2  13.0 

— >      Lengths  removed  in  mm. 
Figure  22      Rana  clamitans.      First  regenerations      Six  days 


16.7 


0.30 
0.20 
0.10 


M 

a 

<D 
O 

1  Figure  23 
X 

Pi 


1.5    2.6        4.6  8.2 

— >■      Lengths  removed  in  mm. 
Rana  clamitans       First  regenerations 


13.0 


16.7 


Specific  lengths     Six  days 


The  maximum  rate  of  regeneration  is  reached  between  the  sixth 
and  the  eighth  day.  The  regenerated  lengths  at  eight  days  are  0.8,  0.7, 
1.5,  1.7,  2.6  and  3.0  mm.  The  data  are  shown  in  Table  41  and  Figure  24. 
With  one  exception  there  is  increase  in  regenerated  length  with  increase 
in  removed  length.  The  specific  regenerated  lengths  are  0.53,  0.27,  0.33, 
0.21,  0.20  and  0.18  as  shown  in  Table  41  and  Figure  25.  The  shortest 
removals  have  the  greatest  specific  regenerations  but  at  8.2  mm.  and 
above  there  is  an  approach  to  constancy. 


79] 


RATE    OF    REGENERATION— ZELENY 


79 


f 

- 


3.0 


2.0 


1.0 


Figure  24 


1.5    2.6         4.6  8.2  13.0 

— >■      Lengths  removed  in  mm. 
Rana  clamitans     First  regenerations     Eight  days 


16.1 


mm. 


0.60 
0.50 
0.40 
0.30 
0.20 
0.10 


1.5 


13.0 


2.6        4.6  8.2 

— >-      Lengths  removed  in  mm. 
Figure  25  Rana  clamitans.        First  regenerations    Specific  lengths 


16.7 


Eight  days 


Between  the  eighth  and  the  tenth  day  there  is  a  rapid  decrease  in 
rate  associated  with  tissue  differentiation.  The  regenerated  lengths  at 
ten  days  are  0.9,  1.0,  1.7,  2.3,  3.8  and  4.5  mm.  as  shown  in  Table  41 
and  Figure  26.  There  is  an  uninterrupted  increase  in  regeneration  with 
increase  in  removed  length.  The  specific  lengths  are  0.58,  0.38,  0.37, 
0.28,  0.29  and  0.27  as  shown  in  Table  41  and  Figure  27. 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[80 


Between  ten  and  twelve  and  a  half  days  regeneration  is  slow,  reach- 
ing its  end  for  the  two  shortest  removals  at  the  latter  day.  The  regen- 
erated lengths  at  twelve  and  a  half  days  are  0.9,  1.2,  1.8,  2.6,  4.7  and 


mm 

5.0 

•a 

4.0 

••-> 

«j 

E 

a> 

§ 

3.0 

M 

4> 

U 

an 

J3 

2.0 

■*-> 

ttf) 

S3 

a> 

1.0 

Figure  26 


1.5 


13.0 


2.6        4.6  8.2 

— >-      Lengths  removed  in  mm. 
Rana  clamitans.   First  regenerations    Ten  days 


16.7 


•a 

mm. 

d 

0.60 

u 

<D 

a 

0.50 

U1 

0.40 

Hi 

0.30 

m 

0.20 

a 

0) 

0.10 

t> 

1$ 

- 

1.5    2.6        4.6  8.2 

— >-      Lengths  removed  in  mm. 


13.0 


16.7 


Figure  27      Rana  clamitans      First  regenerations      Specific  lengths      Ten  days 


5.8  mm.  as  shown  in  Table  42  and  Figure  28.  There  is  a  steady  increase 
with  increase  in  removed  length.  The  specific  lengths  are  0.61,  0.46, 
0.39,  0.31,  0.36  and  0.35  as  shown  in  Table  42  and  Figure  29.  There  is 
an  approach  to  constancy  in  the  four  largest  removals. 


81] 


RATE    OF   REGENERATION —ZELENY 


81 


Between  twelve  and  a  half  and  eighteen  days  the  regenerated 
material  is  decreasing  in  the  case  of  the  two  shortest  removals,  has  made 
no  progress  in  the  third  and  in  the  three  longest  removals  the  increase  is 
very  slight.  The  data  therefore  are  of  value  more  particularly  in  con- 
nection with  the  problem  of  the  relative  completeness  of  regeneration 
from  the  different  levels.    The  regenerated  lengths  at  eighteen  days  are 


mm. 
6.0 

5.0 
4.0 
3.0 
2.0 
1.0 


Figure  28 

*o 

mm. 

<u 

0.70 

a 

h 

9 

0.60 

a 

0.50 

u 

0.40 

00 

.a 

0.30 

5) 

a 

0.20 

_ i 

o 

0.10 

<c 

a 

<u 

Q, 

W 

1.5    2.6        4.6  8.2 

— >■      Lengths  removed  in  mm. 
Rana  clamitans      First  regenerations 


13.0 


16.7 


Twelve  and  a  half  days 


1.5 


13.0 


2.6        4.6  8.2 

— y      Lengths  removed  in  mm. 
Figure  29     Rana  clamitans     First  regenerations     Specific  lengths 
a  half  days 


16.7 


Twelve  and 


82 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[82 


0.9,  1.1,  1.8,  2.7,  5.5  and  6.8  mm.  as  shown  in  Table  42  and  Figure  30. 
There  is  a  regular  increase  with  increase  in  removed  length.  The 
specific  lengths  are  0.60,  0.42,  0.39,  0.33,  0.42  and  0.40  as  shown  in 
Table  42  and  Figure  31.  Though  there  are  irregularities  the  specific 
lengths  approach  constancy  at  all  levels  except  the  most  distal  one. 
Between  eighteen  and  fifty-six  days  there  is  practically  no  increase 


■8 


mm. 
7.0 

6.0 
5.0 
4.0 
3.0 

2.0 
1.0 


Figure  30 


1.5    2.6        4.6  8.2  13.0 

— >      Lengths  removed  in  mm. 
Rana  clamitans.     First  regenerations     Eighteen  days 


16.7 


- 


mm. 
0.70 
0.60 
0.50 
0.40 
0.30 
0.20 
0.10 


Figure  31 
days 


1.5    2.6  4.6  8.2 

— >-      Lengths  removed  in  mm. 
Rana  clamitans       First  regenerations 


13.0 


16.7 


Specific  lengths      Eighteen 


83] 


RATE    OF    REGENERATION— ZELENY 


83 


in  regenerated  length  and  some  absorption  of  material  especially  with 
the  shorter  removals.  The  regenerated  lengths  at  fifty-six  days  are  0.7, 
1.1,  1.5,  2.5,  5.5  and  6.9  mm.  as  shown  in  Table  42  and  Figure  32.  There 
is  a  regular  increase  in  regeneration  from  the  shortest  to  the  longest 
removal.  The  specific  lengths  are  0.45,  0.42,  0.34,  0.30,  0.42  and  0.41 
as  shown  in  Table  42  and  Figure  33.  These  data  are  of  value  only  for 
mm. 

7.0 


6.0 


-%       5.0 


to 

e 


4.0 


3.0 


2.0 


1.0 


Figure  32 

•o 

A 

-u 

■ 

mm. 

V 

a 

0.50 

<D 

M 
S 

0.40 

u 

■ 

0.30 

■fl 

■ 

0.20 

9 

0.10 

o 

c 

o 

<D 

ft 

CD 

Figure  33 


1.5    2.6        4.6  8.2  13.0 

— >■      Lengths  removed  in  mm. 

Ram  clamitans    First  regenerations    Fifty-six  days 


16.7 


1.5 


13.0 


2.6         4.6  8.2 

— y      Lengths  removed  in  mm. 
Rana  clamitans    First  regenerations    Specific  lengths 


16.7 


Fifty-six  days 


84 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[84 


a  comparison  of  completeness  of  regeneration  but  for  such  a  comparison 
it  is  better  in  some  ways  to  compare  the  regenerations  at  the  time  when 
absorption  has  not  begun.  The  greatest  average  regenerated  length 
attained  for  the  1.5  mm.  level  is  0.9  mm.  at  ten  days,  for  the  2.6  level 
1.2  at  twelve  and  a  half  days,  for  the  4.6  level  1.8  at  twelve  and  a  half 
days,  for  the  8.2  level  2.7  at  eighteen  days,  for  the  13.0  level  5.5  at 
eighteen  days  and  for  the  16.7  level  6.9  at  fifty-six  days.  There  is  an 
uninterrupted  increase  from  the  shortest  to  the  longest  removal  in  com- 
plete amount  regenerated.    This  is  shown  graphically  in  Figure  34.   The 

mm. 

7.0 


6.0 


5.0 


4.0 


3.0 


2.0 


1.0 


Figure  34 


1.5    2.6        4.6  8.2  13.0 

— >-      Lengths  removed  in  mm. 
Rana  clamitans      First  regenerations     Completeness 


16.7 


p. 
x 


mm. 
0.70 

0.60 
0.50 
0.40 
0.30 
0.20 
0.10 


1.5    2.6         4.6  8.2  13.0  16.7 

— >-      Lengths  removed  in  mm. 
Figure  35       Rana  clamitans       First  regenerations      Specific  lengths 

Completeness 


85] 


RATE    OF    REGENERATION— ZELENY 


85 


completed  regenerations  are  less  than  the  removed  lengths.  The  specific 
completed  regenerated  lengths  obtained  as  before  by  dividing  by  the 
removed  lengths  are  0.61,  0.46,  0.39,  0.33,  0.42  and  0.41,  as  shown  in 
table  42  and  figure  35.  The  greater  specific  lengths  from  the  shortest 
removals  are  probably  due  as  in  the  case  of  the  second  regenerations 
to  the  fact  that  a  greater  proportion  of  their  substance  is  made  up  of 
cells  that  have  migrated  over  the  cut  surface  during  the  first  stages  of 
regeneration.  This  migrated  material  is  not  essentially  different  in  axial 
length  at  the  different  levels.  The  largest  removals  have  a  greater  spe- 
cific length  than  the  medium  ones  because  regeneration  continues  at  the 
former  levels  after  it  has  ceased  at  the  latter. 

On  the  whole  there  is  no  essential  difference  between  the  results 
obtained  from  first  regenerations  and  those  obtained  from  second  regen- 
erations. The  latter  give  the  more  regular  data  because  the  averages  are 
taken  from  a  larger  number  of  individuals. 


Rana  clamitans 


TABLE  41 

Series  3676-3765 


First  regenerations 


Catalog 
number 

Removed 
length 

in 
mm. 

4   Days 

6   Days 

8  Days 

10  Days 

Percent 
removed 
Average 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

3706 

1.4 

0.24 

0.54 

0.9 

1.0 

6 

3742 

1.7 

0.30 

0.40 

0.7 
0.8 

0.8 
0.9 

Average 

1.5 

0.27 

0.17 

0.47 

0.30 

0.53 

0.58 

3688 

2.5 

0.12 

0.3 

0.3 

0.7 

3707 

3.2 

0.24 

0.8 

1.1 

1.4 

3724 

2.6 

0.06 

0.5 

0.8 

1.1 

10 

3743 

2.5 

0.03 

0.1 

0.4 

0.8 

3760 

3.1 

0.30 

0.6 

0.9 
0.7 

1.1 
1.0 

Average 

2.6 

0.15 

0.06 

0.5 

0.18 

0.27 

0.38 

86 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[86 


TABLE  41 

(Continued) 

Catalog 
number 

Removed 
length 

in 
mm. 

4    Days 

6   Days 

8  Days 

10 

Regen- 
erated 
length 
mm. 

Days 

Percent 
removed 
Average 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Specific 
length 

3708 

5.3 

0.54 

1.2 

1.9 

2.1 

3726 

4.3 

0.42 

0.9 

1.3 

1.4 

17 

3762 

4.1 

0.57 

1.0 

1.2 

1.5 
1.7 

Average 

4.6 

0.51 

0.11 

1.0 

0.22 

1.5 

0.33 

0.37 

3690 

9.7 

0.48 

1.0 

1.7 

2.4 

3709 

8.8 

0.48 

1.3 

2.0 

2.6 

3727 

8.3 

0.48 

1.1 

1.6 

2.0 

3745 

10.0 

0.54 

1.8 

2.4 

3.8 

3744 

6.0 

0.36 

1.0 

1.3 

1.7 

30 

3761 

6.6 

0.39 

1.0 

1.5 

1.9 

3763 

8.5 

0.57 

1.1 

1.8 

2.4 

3689 

6.3 

0.30 

0.05 

0.7 

1.2 
1.7 

1.5 
2.3 

~ 

Average 

'3.2 

0.45 

1.1 

0.13 

0.21 

0.28 

3710 

12.3 

0.42 

1.8 

2.9 

3.7 

3728 

12.8 

0.60 

1.7 

2.8 

3.9 

3746 

13.3 

0.54 

1.7 

2.4 

4.1 

48 

3764 

14.6 

0.42 

1.3 

2.5 

4.2 

3765 

12.2 

0.30 

1.5 

2.3 
2.6 

3.2 

3.8 

Average 

13.0 

0.46 

0.03 

1.6 

0.12 

0.20 

0.29 

3692 

16.8 

0.51 

1.1 

2.2 

3.2 

3693 

17.2 

0.48 

1.8 

3.3 

5.0 

3711 

17.0 

0.54 

1.8 

3.6 

5.6 

62 

3729 

16.1 

0.48 

1.9 

3.3 

4.6 

3749 

16.2 

0.54 

1.2 

2.7 
3.0 

0.18 

4.2 
4.5 

Average 

16.7 

0.51 

0.03 

1.6 

0.09 

0.27 

87] 


RATE    OF    REGENERATION —ZELENY 


87 


TABLE  42 


Rana  clamitans 

Series 

3676-3765            First  regenerations 

\ 

Catalog 
number 

Re- 
moved 
length 
in  mm. 

124  Days 

18  Days 

56 

Days 

Percent 
removed 
Average 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

Regen- 
erated 
length 
mm. 

Specific 
length 

3706 

1.4 

1.0 

0.9 

0.7 

6 

3742 

1.7 
1.5 

0.9 

0.9 

0.7 

Average 

0.9 

0.61 

0.9 

0.60 

0.7 

0.45 

3688 

2.5 

0.9 

0.9 

0.7 

3707 

3.2 

1.4 

1.3 

0.7 

3724 

2.6 

1.4 

1.4 

1.2 

10 

3743 

2.5 

1.0 

1.0 

1.7 

3760 

3.1 
2.6 

1.2 

1.1 

1.1 

Average 

1.2 

0.46 

1.1 

0.42 

1.1 

0.42 

3708 

5.3 

2.3 

2.3 

1.8 

3726 

4.3 

1.4 

1.4 

1.4 

17 

3762 

4.1 

1.7 

1.8 

1.4 

Average 

4.6 

1.8 

0.39 

1.8 

0.39 

1.5 

0.34 

3690 

9.7 

2.6 

2.7 

2.2 

3709 

8.8 

3.2 

3.4 

3.3 

3727 

8.3 

2.2 

2.2 

2.2 

3745 

10.0 

4.4 

4.8 

4.2 

3744 

6.0 

1.8 

1.7 

30 

3761 
3763 

6.6 
8.5 

2.2 
2.9 

2.3 
3.1 

1.8 

3689 

6.3 

1.6 

1.7 

1.4 

Average 

8.2 

2.6 

0.31 

2.7 

0.33 

2.5 

0.30 

3710 

12.3 

3.9 

3.9 

3.9 

3728 

12.8 

4.8 

5.4 

5.8 

3746 

13.3 

5.7 

7.0 

6.8 

48 

3764 

14.6 

5.3 

6.8 

6.5 

3765 

12.2 

3.9 

4.5 

4.5 

Average 

13.0 

4.7 

0.36 

5.5 

0.42 

5.5 

0.42 

3692 

16.8 

4.3 

5.0 

5.2 

3693 

17.2 

6.5 

7.3 

6.6 

3711 

17.0 

7.0 

7.7 

8.3 

62 

3729 

16.1 

5.5 

6.7 

6.4 

3749 

16.2 

5.6 

7.1 

7.8 

Average 

16.7 

5.8 

0.35 

6.8 

0.40 

6.9 

0.41 

88  ILLINOIS    BIOLOGICAL    MOXOGRAPHS 

TABLE  43 

Rana    clamitans       Series    3676-3765       Summary       First    regenerations 

Lengths  regenerated  at  different  levels  at  different  times 


Percent  of 

tail  length 

removed 

Length 

removed 

in  mm. 

Number 
of  indi- 
viduals 

Days  after  operation 

4 

6 

8 

10 

12J4 

18 

56 

6 

1.5 

2 

0.27 

0.5 

0.8 

0.9 

0.9 

0.9 

0.7 

10 

2.6 

5 

0.15 

0.5 

0.7 

1.0 

1.2 

1.1 

1.1 

17 

4.6 

3 

0.51 

1.0 

1.5 

1.7 

1.8 

1.8 

1.5 

30 

8.2 

8 

0.45 

1.1 

1.7 

2.3 

2.6 

2.7 

2.5 

48 

13.0 

5 

0.46 

1.6 

2.6 

3.8 

4.7 

5.5 

5.5 

62 

16.7 

5 

0.51 

1.6 

3.0 

4.5 

5.8 

6.8 

6.9 

TABLE  44 

Rana   clamitans       Series    3676-3765       Summary       First    regenerations 

Specific  lengths  regenerated  at  different  levels  at  different  times 


Percent  of 

tail  length 

removed 

Length 

removed 

in  mm. 

Number 
of  indi- 
viduals 

Days  after  operation 

4 

6 

8 

10 

\V/z 

18 

56 

6 

1.5 

2 

0.17 

0.30 

0.53 

0.58 

0.61 

0.60 

0.45 

10 

2.6 

5 

0.06 

0.18 

0.27 

0.38 

0.46 

0.42 

0.42 

17 

4.6 

3 

0.11 

0.22 

0.33 

0.37 

0.39 

0.39 

0.34 

30 

8.2 

8 

0.05 

0.13 

0.21 

0.28 

0.31 

0.33 

0.30 

48 

13.0 

5 

0.03 

0.12 

0.20 

0.29 

0.36 

0.42 

0.42 

62 

16.7 

5 

0.03 

0.09 

0.18 

0.27 

0.35 

0.40 

0.41 

Experiment  II  Amblystoma  punctatum  Series  4600-5052 
The  eggs  were  hatched  on  March  29  to  April  4,  1913.  Opera- 
tions on  the  tail  were  made  on  May  7  in  numbers  4600-4752  and  on  May 
10  in  numbers  4800-5052.  The  removed  lengths  were  approximately 
Vio>  Vs*  Vs>  Vs  ^d  3A  of  the  tail  length.  Measurements  of  the  regen- 
erated tissue  were  made  at  2,  4,  6,  8-9,  10-11,  13,  15-16  and  17-18  days 
after  the  operation.  The  data  are  given  in  Tables  45  to  54  and  in  Figures 
36  to  51. 

The  salamander  larvae  are  much  more  irregular  in  their  regeneration 
as  well  as  in  ordinary  growth  than  frog  tadpoles.     The  measurements 


89]  RATE    OF    REGENERATION— ZELENY  89 

in  the  present  experiment  were  made  on  killed  individuals  so  that  only 
a  single  regeneration  measurement  is  made  in  a  single  individual.  This 
procedure  also  tends  toward  a  greater  variability  in  the  data.  The 
number  of  individuals  in  any  particular  measurement  also  is  less  than 
for  the  second  regeneration  of  frog  tadpoles. 

Notwithstanding  all  these  unwelcome  factors  the  general  features 
of  regeneration  are  similar  to  those  for  the  tadpole  experiment.  The 
regenerated  length  at  any  time  is  approximately  proportional  to  the 
removed  length.  It  is  true  even  in  the  earliest  measurements.  As 
for  frog  tadpoles  the  shorter  removals  have  proportionately  a  larger 
regeneration  than  the  others  at  practically  each  time  of  measurement. 
The  approach  to  equality  in  specific  lengths  is  true  only  of  the  lengths 
of  removal  equal  to  one-fifth  or  more  of  the  tail  length. 

At  two  days  the  regenerated  lengths  are  respectively  0.10,  0.15, 
0.15,  0.47  and  0.53  mm.  for  the  five  levels  of  removal.  They  give  specific 
lengths  of  0.07,  0.07,  0.04,  0.08  and  0.06  as  shown  Table  45  and  Figures 
36  and  37. 

At  four  days  the  regenerated  lengths  are  0.12,  0.15,  0.30,  0.41  and 
0.40  mm.  and  the  specific  lengths  0.11,  0.07,  0.07,  0.07  and  0.05  as  shown 
in  Table  46  and  Figures  38  and  39. 

At  six  days  the  regenerated  lengths  are  0.32,  0.47,  0.62,  0.70  and 
1.02  mm.  and  the  specific  lengths  0.30,  0.20,  0.16,  0.12  and  0.11  as  shown 
in  Table  47  and  Figures  40  and  41. 

At  eight  to  nine  days  the  regenerated  lengths  are  0.40,  0.65,  0.80, 
1.40  and  1.52  mm.  and  the  specific  lengths  0.44,  0.28,  0.23,  0.23  and 
0.19  as  shown  in  Table  48  and  Figures  42  and  43. 

At  ten  to  eleven  days  the  regenerated  lengths  are  0.50,  0.63,  1.54, 
2.22  and  2.22  mm.  and  the  specific  lengths  0.62,  0.26,  0.43,  0.41  and 
0.27  as  shown  in  Table  49  and  Figures  44  and  45. 

At  thirteen  days  the  regenerated  lengths  are  0.78,  0.92,-  1.74,  2.40 
and  3.60  mm  and  the  specific  lengths  0.74,  0.43,  0.48,  0.44  and  0.48  as 
shown  in  Table  50  and  Figures  46  and  47. 

At  fifteen  to  sixteen  days  the  regenerated  lengths  are  0.80,  1.30, 
1.37,  2.80  and  3.80  mm.  and  the  specific  lengths  0.67,  0.61,  0.40,  0.48  and 
0.54  as  shown  in  Table  51  and  Figures  48  and  49. 

At  seventeen  to  eighteen  days  the  regenerated  lengths  are  0.70, 
1.40,  1.60,  3.80  and  4.67  mm.  and  the  specific  lengths  0.67,  0.62,  0.41, 
0.66  and  0.57  as  shown  in  Table  52  and  Figures  50  and  51. 

A  summary  of  regenerated  lengths  is  given  in  Table  53  and  of 
specific  regenerated  lengths  in  Table  54. 

Since  the  experiment  was  closed  at  eighteen  days  and  since  the 
measurements  at  different  times  were  made  on  different  individuals  it 
is  not  possible  to  make  as  accurate  a  comparison  of  completeness  of 


90 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[90 


regeneration  as  in  the  case  of  the  frog  tadpoles.  For  the  three  shortest 
removals  regeneration  is  probably  completed  at  this  time  but  this  is  not 
true  for  the  two  longest  ones.  In  this  respect  as  in  others  there  is  an 
agreement  with  the  former  experiment.  The  percent  of  the  removed 
tail  that  is  regenerated  is  greater  for  all  levels  than  in  the  frog  tadpoles. 
It  is  probable  also  that  if  the  longest  removals  had  been  allowed  to  com- 
plete their  regenerations  their  specific  regenerations  as  in  the  case  of 
the  frog  tadpoles  would  have  been  shown  to  be  greater  than  those  for 
medium  levels. 

TABLE  45 

Amblystoma  punctatum.        Series  4600-5052.        Average  tail  length  =10.9  mm. 

Regeneration:  2  days 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

14 

5022 

1.5 

0.1 

Average  . 

1.5 

0.10 

0.07 

4641 

2.3 

0.2 

4741 

1.9 

0.1 

20 

4841 

2.2 

0.1 

5050b 

2.3 

0.2 

Average 

2.2 

0.15 

0.07 

4811 

3.9 

0.3 

4911 

3.3 

0.1 

32 

5012 

3.3 

0.05 

Average 

3.5 

0.15 

0.04 

4601 

6.0 

0.3 

4801 

6.0 

0.7 

53 

5001 

5.4 

0.4 

Average 

5.8 

0.47 

0.08 

4631 

9.5 

0.7 

4831 

9.1 

0.6 

81 

5032 

7.9 

0.3 

Average 

8.8 

0.53 

0.06 

91] 


RATE    OF    REGENERATION— ZELENY 


91 


The  data  from  both  experiments  show  that  except  for  very  short 
removals  the  length  regenerated  in  a  given  time  is  approximately  pro- 
portional to  the  length  removed. 

TABLE  46 
Amblystoma  punctatum.       Series  4600-5052.         Average  tail  length— 10.9  mm. 

Regeneration:  4  days 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

4622 

0.9 

0.1 

4722 

0.8 

0.2 

4822 

1.5 

0.1 

10 

4922 

0.8 

0.1 

5024 

1.6 

0.1 

Average 

1.1 

0.12 

0.11 

4742 

2.4 

0.1 

21 

4842 

2.3 

0.2 

I 

Average 

2.3 

0.15 

0.07 

4612 

3.7 

0.3 

4712 

3.6 

0.2 

37 

4812 

4.5 

0.4 

5012 

4.2 

0.3 

Average 

4.0 

0.30 

0.07 

4602 

6.0 

0.2 

4702 

6.0 

0.05 

4802 

6.2 

0.7 

55 

4902 

6.0 

0.5 

5004 

5.9 

0.6 

Average 

6.0 

0.41 

0.07 

4632 

9.3 

0.4 

4732 

8.5 

0.2 

4832 

10.9 

0.6 

76 

4932 

5.9 

0.4 

5034 

7.1 

0.4 

Average 

8.3 

0.40 

0.05 

92 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[92 


Amblystoma   punctatum. 


TABLE  47 
Series   4600-5052.       Average  tail  length=10.9   mm. 
Regeneration:  6  days 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific    . 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

4623 

1.0 

0.3 

4723 

0.8 

0.2 

10 

4923 

1.6 

0.6 



1.1 

0.2 

Average 

1.1 

0.32 

0.30 

4643 

2.1 

0.7 

4743 

2.2 

0.2 

21 

4843 

2.1 

0.4 

4943 

2.8 

0.6 

Average 

2.3 

0.47 

0.20 

4613 

3.6 

0.6 

4713 

2.9 

0.6 

4820b 

4.4 

0.8 

35 

4913 

4.5 

0.6 

5013 

3.6 

0.5 

Average 

3.8 

0.62 

0.16 

4603 

6.1 

0.4 

4703 

6.7 

0.4 

54 

4803 

5.3 

1.4 

5003 

5.6 

0.6 

Average 

5.9 

0.70 

0.12 

4633 

8.8 

0.6 

4733 

8.2 

0.9 

82 

4833 

10.6 

1.8 

5033 

7.9 

0.8 

Average 

8.9 

1.02 

0.11 

93] 


RATE    OF    REGENERATION  —  ZELENY 


93 


TABLE  48 
Amblystoma    punctatum       Series    4600-5052      Average    tail    length— 10.9 
Regeneration:  8-9  days  (8  for  4800-5052,  9  for  4600-4752) 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

4724 

0.7 

0.2 

4824 

1.1 

0.7 

8 

5026 

1.0 

0.3 

Average 

0.9 

0.40 

0.44 

4644 

2.3 

0.6 

4844 

2.3 

1.0 

21 

4944 

2.2 

0.7 

- 

5045 

2.3 

0.3 

Average 

2.3 

0.65 

0.28 

4614 

3.0 

0.8 

4624 

3.0 

0.4 

4714 

3.4 

1.2 

31 

4814 

3.7 

1.0 

4914 

3.2 

0.6 

5016 

4.3 

0.8 

Average 

3.4 

0.80 

0.23 

4604 

6.0 

1.8 

4704 

6.3 

1.7 

4804 

5.9 

1.4 

56 

4904 

5.4 

0.9 

5006 

6.8 

1.2 

Average 

6.1 

1.40 

0.23 

4634 

8.3 

2.1 

4734 

8.0 

1.3 

4834 

9.0 

1.6 

75 

4934 

7.5 

1.1 

Average 

8.2 

1.52 

0.19 

94 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[94 


TABLE  49 
Amblystoma    punctatum       Series    4600-5052      Average    tail    length=10.9 
Regeneration:  10-11  days  (10  for  4800-5052,  11  for  4600-4752) 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

4725 

0.6 

0.3 

4825 

0.8 

0.6 

7 

5027 

1.0 

0.6 

Average 

0.8 

0.50 

0.62 

4746 

2.6 

0.4 

4845 

2.6 

1.0 

23 

5046 

2.2 

0.5 

Average 

2.5 

0.63 

0.26 

4620b 

3.0 

1.9 

4715 

3.0 

1.8 

4815 

4.3 

2.0 

33 

4920 

3.6 

1.2 

5017 

3.9 

0.8 

Average 

3.6 

1.54 

0.43 

4605 

5.2 

2.8 

4705 

4.6 

1.4 

4805 

6.3 

2.8 

50 

4910b 

5.0 

1.9 

5007 

6.0 

2.2 

Average 

5.4.. 

2.22 

0.41 

4735 

7.5 

2.5 

4835 

9.4 

2.9 

74 

4935 

7.6 

1.3 

5037 

8.1 

2.2 

Average 

8.1 

2.22 

0.27 

95] 


RATE    OF    REGENERATION— ZELENY 


95 


Ambly.stoma  punctatum. 


TABLE  50 

Series  4600-5052.       Average  tail  length=10.9  mm. 
Regeneration:  13  days 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

4626 

1.4 

0.8 

4726 

1.0 

0.6 

4830b 

1.0 

0.7 

10 

4926 

1.0 

0.9 

5028 

0.9 

0.9 

Average 

1.1 

0.78 

0.74 

4646 

1.9 

1.4 

4745 

2.2 

0.8 

19 

4846 

2.6 

1.0 

4946 

1.9 

0.5 

Average 

2.1 

0.92 

0.43 

4616 

3.6 

1.8 

4716 

3.2 

2.0 

4816 

3.9 

2.5 

32 

4916 

3.7 

1.6 

5018 

3.7 

0.8 

Average 

3.6 

1.74 

0.48 

4706 

6.4 

2.3 

4806 

5.8 

2.9 

50 

4910 

5.0 

2.5 

5008 

4.5 

1.9 

Average 

5.4 

2.40 

0.44 

4636 

8.1 

3.4 

4740b 

7.7 

4.7 

69 

4936 

7.4 

3.5 

5038 

6.7 

2.8 

Average 

7.5 

3.60 

0.48 

96 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[96 


TABLE  51 

Amblystoma  punctatum.       Series   4600-5052.       Average  tail  length=10.9   mm. 

Regeneration:  15-16  days  (15  for  4800-5052,  16  for  4600-47g2) 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

4927 

1.2 

0.8 

11 

5029 

1.2 

0.8 

Average 

1.2 

0.80 

0.67 

4647 

1.9 

1.5 

4747 

2.7 

1.7 

4847 

2.4 

1.0 

19 

4950b 

1.9 

1.2 

5049 

1.8 

1.1 

Average 

2.1 

1.30 

0.61 

4617 

3.1 

1.4 

4717 

3.5 

1.3 

32 

4917 

3.2 

1.8 

5019 

4.1 

1.0 

Average 

3.5 

1.37 

0.40 

4607 

5.7 

2.7 

4807 

5.7 

2.9 

53 

4817 

5.2 

2.6 

5009 

6.6 

3.0 

Average 

5.8 

2.80 

0.48 

64 

4937 

7.0 

3.8 

Average 

7.0 

3.80 

0.54 

97] 


RATE    OF    REGENERATION —ZELENY 


97 


TABLE  52 
Amblystoma  punctatum.       Series   4600-5052.       Average   tail   length=10.9   mm. 
'  Regeneration:  17-18  days  (18  for  4800-5052,  17  for  4600-4752) 


Percent  of 

tail  length 

Catalog 

Removed 

Regenerated 

Specific 

removed 

number 

length 

length 

length 

Average 

mm. 

mm. 

regenerated 

4828 

1.0 

0.8 

10 

4929 

1.1 

0.6 

Average 

1.0 

0.70 

0.67 

4648 

2.1 

1.5 

4749 

2.6 

2.1 

4848 

2.1 

1.1 

20 

4949 

2.2 

1.3 

5050 

2.2 

1.0 

Average 

2.2 

1.40 

0.62 

4718 

3.9 

1.6 

36 

Average 

3.9 

1.60 

0.41 

4608 

5.4 

4.2 

4708 

6.6 

4.1 

53 

4808 

5.4 

3.1 

Average 

5.8 

3.80 

0.66 

4838 

9.4 

5.0 

4939 

6.4 

4.5 

76 

5040 

9.0 

4.5 

Average 

8-3 

4.67 

0.57 

98 


ILLINOIS    BIOLOGICAL    MONOGRAPHS 


[98 


TABLE  53 

Amblystoma  punctatum       Series  4600-5052       Summary      Regenerated  lengths 

(Tables  45  to  52) 


Percent  of 

tail  length 

removed 

Average 

Length 
removed 

mm. 
Average 

Ave 

•age    le 

ngth    regenerated    in 

mm. 

2 
Days 

4 
Days 

6 
Days 

8-9 
Days 

10-11 

Days 

13 
Days 

15-16 
Days 

17-18 
Days 

10 

1.1 

0.10 

0.12 

0.32 

0.40 

0.50 
0.63 

0.78 
0.92 

0.80 

0.70 

21 

2.2 

0.15 

0.15 

0.47 

0.65 
0.80 
1.40 

1.30 

1.40 

34 

3.7 

0.15 

0.30 

0.62 

1.54 

1.74 

1.37 

1.60 

53 

5.8 

0.47 

0.41 

0.70 

2.22 

2.40 
3.60 

2.80 

3.80 

74 

8.1 

0.53 

0.40 

0.94 

1.52 

2.22 

3.80 

4.70 

TABLE  54 
Amblystoma  punctatum   Series  4600-5052   Summary   Specific  lengths  regenerated 

(Tables  45  to  52) 


Percent  of 

tail   length 

removed 

Average 

Length 
removed 

mm. 
Average 

Ave 

rage  specific  regenerated  len 

gths 

2 
Days 

4 
Days 

6 
Days 

8-9 
Days 

10-11 
Days 

13 
Days 

15-16 
Days 

17-18 
Days 

10 

1.1 

0.07 

0.11 

0.30 

0.43 

0.62 

0.74 

0.67 

0.67 

21 

2.2 

0.07 
0.04 

0.06 

0.20 

0.28 

0.26 

0.43 

0.61 

0.62 

34 

3.7 

0.07 

0.16 

0.23 

0.43 

0.48 

0.40 

0.41 

53 

5.8 

0.08 

007 

0.12 
0.11 

0.23 

0.41 

0.44 
0.48 

0.48 

0.66 

74 

8.1 

0.06 

0.15 

0.19 

0.27 

0-54 

0.57 

99] 


RATE    OF    REGENERATION— ZELENY 


99 


mm. 
0.67 


1 

g 
Figure  36 


1.5     2.2  3.5  5.8 

— >■      Lengths  removed  in  mm. 
Amblystoma   punctatum       Lengths  regenerated 


8.8 


Two  days 


mm. 
0.10 


«  Figure  37 


1.5      2.2  3.5  5.8  8.8 

— >-      Lengths  removed  in  mm. 
Amblystoma  punctatum       Specific  lengths  regenerated    Two  days 


_ 


.2    mm. 
I     0.67 

i 

© 

M 


i 

13  1.1 

J  — 

Figure  38  Amblv stoma 


2.3  4.0  6.0 

■>-      Lengths  removed  in  mm. 
punctatum     Lengths  regenerated 


8.3 


Four  days 


§ 


mm. 
0.10 


1.1 


6.0 


2  Figure  39 


2.3  4.0 

— >-      Lengths  removed  in  mm. 
Amblystoma  punctatum       Specific  lengths  regenerated 


8.3 


Four  days 


- 


100 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


100 


bo 

a 

© 


mm. 
0.67 


Figure  40 


1.1  2.3  3.8  5.9 

— >-      Lengths  removed  in  mm. 
Amblystoma  punctatum       Lengths  regenerated 


8.9 


Six  days 


to 

s 

o 


mm. 
0.30 
0.20 
0.10 


»  Figure  41 

to 


mm. 
1.33 


1.1  2.3  3.8  5.9  8.9 

— >-      Lengths  removed  in  mm. 
Amblystoma  punctatum       Specific  lengths  regenerated     Six  days 


0.67 


s 


0.9 


6.1 


8.2 


2.3  3.4 

— >■      Lengths  removed  in  mm. 
Figure  42     Amblystoma  punctatum      Lengths  regenerated     Eight  to  nine  days 

%         mm. 
g  0.50 

g  0.40 

bfl 

Z  0.30 

3  0.20 

M 

g         0.10 


0.9 


6.1 


2.3  3.4 

— >■      Lengths  removed  in  mm. 
Figure  43     Amblystoma  punctatum         Specific  lengths  regenerated 
nine  days 


8.2 


Eight  to 


101] 


RATE   OF  REGENERATION— ZELENY 


101 


2.00 


1.33 


0.67 


0.8  2.5  3.6  5.4 

— >■      Lengths  removed  in  mm. 
Figure  44     Amblystoma  punctatum     Lengths  regenerated 


8.1 


Ten  to  eleven  days 


— 

0.60 

0.50 

to 

0.40 

■- 

10 

0.30 

i2 
o 

0.20 

0.10 

- 

X 

0.8  2.5          3.6                   5.4                               8.1 

— >■  Lengths  removed  in  mm. 

Figure    45     Amblystoma  punctatum         Specific    lengths    regenerated      Ten    to 
eleven  days 


102 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[102 


fee 
d 
5 


mm. 
3.33 

2.67 

2.00 

1.33 

0.67 


1.1  2.1  3.6  5.4  7.5 

— y      Lengths  removed  in  mm. 
Figure  46    Amblystoma  punctatum      Lengths  regenerated    Thirteen  days 


mm 

T) 

0.70 

a 

0.60 

a 

0.50 

0> 

l-> 

OS 

0.40 

.3 

0.30 

o 

""* 

0.20 

o 

<p 

1 

0.10 

a 

CO 

Figure  47 


1.1 


7.5 


2.1  3.6  5.4 

— ►      Lengths  removed  in  mm. 
Amblystoma  punctatum    Specific  lengths  regenerated    Thirteen  days 


103] 


RATE  OF  REGEXERATIOX —ZELENY 


103 


f 

1 

a; 


mm. 
4.00 


3.33 


*g       2.67 


2.00 


1.33 


0.67 


1.2         2.1  3.5  5.8  7.0 

— >-      Lengths  removed  in  mm. 

Figure  48      Amblystoma  punctatum       Lengths  regenerated 
days 


Fifteen  to  sixteen 


0.70 

09"0 
0.50 

0.40 
0.30 


i>      0.20 


0.10 


1.2 


5.8 


2.1  3.5 

— >■      Lengths  removed  in  mm. 
Figure  49     Amblystoma   punctatum       Specific  lengths  regenerated 
sixteen  days 


7.0 


Fifteen  to 


104 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[104 


5 

a 


mm. 
4.67 

4.00 

3.33 

2.67 

2.00 

1.33 

0.67 


1-0  2.2  3.9  5.8  8.3 

— >-  Lengths  removed  in  mm. 

Figure  50     Amblystoma  punctatum      Lengths  regenerated     Seventeen  to  eight- 
een days 


mm 

0.70 

— 

cti 

0.60 

s 

bo 
u 

0.50 

00 

0.40 

J3 

fi 

0.30 

a 

0.20 

o 

S 

0.10 

00 


1.0 


5.8 


2.2  3.9 

— ►■      Lengths  removed  in  mm. 
Figure  51     Amblystoma  punctatum        Specific  lengths  regenerated 
to  eighteen  days 


8.3 


Seventeen 


105]  RATE  OF  REGENERATION— ZELENY  105 


Discussion 

That  the  level  of  the  cut  has  an  important  influence  upon  the  rate 
of  regeneration  has  been  made  out  by  a  number  of  investigators  (Spal- 
lanzani  1768,  King  1898,  Morgan  1906,  Stockard  1908,  Ellis  1909,  Morgu- 
lis  1909a,  b,  and  others).  Their  work  indicates  that  regenerations  from 
deeper  levels  are  on  the  whole  more  rapid  that  from  more  superficial  ones. 
The  data  obtained  from  the  present  experiments  confirm  this  conclusion 
and  make  possible  a  further  analysis  of  the  relation.  They  show  that 
in  the  regeneration  of  the  tail  of  amphibian  larvae  there  is  a  striking 
relation  between  the  level  of  the  cut  and  the  rate  of  regeneration. 
Within  wide  limits  the  length  regenerated  is  directly  proportional  to 
the  distance  of  the  cut  surface  from  the  original  tip  of  the  tail.  Within 
these  limits  therefore  regeneration  at  any  particular  time  after  the 
operation  has  the  same  degree  of  completeness  from  all  levels  of  injury. 

An  analysis  of  the  progress  of  the  regeneration  brings  out  the  fact 
that  two  distinct  periods  are  to  be  recognized  in  rate  of  regeneration 
in  its  relation  to  level  of  the  cut.  During  the  first  two  to  four  days 
after  the  operation  regeneration  is  confined  to  cell  migration  from  the 
old  tissues  without  cell  division.  During  this  period  in  the  frog  tad- 
poles there  is  no  essential  difference  in  length  regenerated  at  the  differ- 
ent levels  and  the  specific  rate  is  therefore  much  greater  after  shorter 
than  after  longer  removals.  In  the  second  period  with  the  initiation 
of  rapid  cell  multiplication  the  rate  of  regeneration  is  greater  the  deeper 
the  level  and  furthermore  is  directly  proportional  to  the  length  removed. 
As  soon  as  the  bulk  of  material  produced  by  cell  division  is  considerably 
greater  than  that  which  was  produced  by  cell  migration  there  is  an 
approach  to  constancy  in  specific  length  regenerated.  This  holds  for  all 
except  the  shortest  removals.  After  the  shortest  removals  the  total 
regeneration  is  so  small  in  amount  that  a  large  part  of  it  is  made  up 
of  the  original  migrated  material.  Therefore  from  these  levels  the  spe- 
cific regenerated  lengths  are  greater  than  from  the  deeper  levels  even 
at  a  late  period  of  regeneration. 

A  further  complication  is  introduced  by  the  fact  that  regeneration 
is  not  complete.  Only  a  certain  per  cent  of  the  removed  length  is  re- 
placed and  the  end  of  the  process  is  reached  sooner  after  the  shorter 
than  after  the  longer  removals.  From  the  deepest  levels  regeneration 
is  still  proceeding  when  it  has  stopped  from  the  medium  and  shallowest 
ones.  When  the  process  is  completed  in  all  cases  the  specific  length  is 
therefore  slightly  greater  after  both  the  longest  and  the  shortest  re- 
movals than  after  medium  ones. 

As  to  the  cause  of  the  difference  in  rate  at  the  different  levels 


106  ILLINOIS  BIOLOGICAL   MONOGRAPHS  [106 

little  more  can  be  said  than  that  it  does  not  seem  to  be  due  to  inherent 
differences  in  the  cells  at  the  different  levels.  If  differentiation  in  the 
tail  proceeded  from  the  tip  toward  the  base,  the  more  rapid  rate  from 
the  more  basal  levels  might  be  explained  by  the  more  embryonic  char- 
acter of  the  cells  at  these  levels.  As  the  tip  is  approached  the  material 
would  become  more  and  more  inert.  There  is  however  no  evidence 
that  differentiation  proceeds  in  this  way  in  this  case. 

The  progressive  increase  in  rate  with  depth  of  level  of  the  cut  is 
undoubtedly  due  to  reactions  which  involve  a  more  central  control,  a 
co-ordination  of  the  functional  activity  as  a  whole.  The  period  of  cell 
migration  probably  is  only  slightly  subject  to  such  control.  It  is  a 
period  in  which  the  response  is  largely  local  in  character  and  there  is 
correspondingly  little  if  any  difference  at  the  different  levels.  The 
rate  of  cell  division  which  is  the  important  factor  during  the  period 
of  rapid  increase  in  length  is  however  undoubtedy  under  central  control. 

Summary 

1.  In  frog  and  salamander  larvae  with  removed  tail  lengths  of 
one-fifth  to  two-thirds,  the  general  rule  holds  that  the  length  regenerated 
in  a  given  time  is  proportional  to  the  length  removed,  or  in  other  words 
the  length  regenerated  per  unit  of  removed  length  is  a  constant. 

2.  An  analysis  of  the  data  shows  however  that  this  applies  only 
to  the  material  produced  by  active  cell  division. 

3.  During  the  first  four  days,  in  frog  tadpoles,  when  the  regener- 
ating part  is  made  up  almost  entirely  of  cells  that  have  migrated  from 
the  old  tissues  without  division  there  is  no  such  relation  between  length 
removed  and  length  regenerated.  The  length  of  new  material  at  this 
time  is  not  strikingly  different  for  the  different  levels  and  the  process 
seems  to  be  a  local  response  of  the  cells  to  the  injury.  The  length 
regenerated  per  unit  of  removed  length  is  greater  at  this  time  for  the 
shorter  than  for  the  longer  removals. 

4.  Since  comparatively  a  large  part  of  the  regenerating  material 
after  the  shorter  removals  is  made  up  of  migrated  cells  even  at  the 
later  periods  it  follows  that  the  specific  regenerations  from  these  levels 
are  greater  than  from  the  deeper  ones. 

5.  During  the  later  periods  the  specific  regenerated  lengths  tend 
to  be  higher  after  both  the  shortest  and  the  longest  removals  than  after 
medium  ones.  In  the  case  of  the  shortest  ones  this  is  due  to  the  rela- 
tively large  part  of  the  whole  regenerated  tail  that  is  made  up  of  mi- 
grated cells.  In  the  case  of  the  longest  removals  it  is  due  to  the  fact 
that  regeneration  continues  for  a  time  after  it  has  stopped  in  the  medium 
ones. 


107]  RATE  OF  REGENERATION— ZELENY  107 

6.  It  does  not  seem  probable  that  the  differences  in  length  regener- 
ated at  different  levels  can  be  due  to  differences  in  the  original  character 
of  the  cells  involved  in  the  process.  Such  a  well  graduated  difference 
in  cell  capacities  is  difficult  to  conceive.  The  process  must  be  under  a 
more  central  control,  probably  connected  with  general  functional 
activity. 


108  ILLINOIS  BIOLOGICAL   MONOGRAPHS  [108 


PART  IV 

THE  CHANGE  IN  RATE  OF  REGENERATION  DURING  THE 

REGENERATIVE  PROCESS 

The  present  experiments  were  undertaken  in  extension  of  previous 
studies  on  the  change  in  rate  throughout  the  regenerative  cycle.  This 
previous  work  showed  that  the  increase  in  amount  of  material  during 
regeneration  follows  the  general  rule  of  increase  during  an  ordinary 
life  cycle.  The  rate  is  at  first  very  slow,  then  increases  very  rapidly 
to  a  maximum,  then  declines  rapidly  at  first  and  then  more  and  more 
slowly  as  zero  is  approached. 

Frog  tadpoles  and  salamander  larvae  were  used  in  the  present 
study.  Large  tadpoles  of  Rana  clamitans  which  remained  fairly  con- 
stant in  size  during  the  course  of  the  experiments  were  found  to  be  the 
most  satisfactory.  The  results  obtained  from  them  were  uniform  enough 
for  an  analysis  of  the  change  in  rate.  The  salamander  larvae  showed 
a  great  variation  in  rate  from  day  to  day  apparently  associated  with 
external  factors  such  as  food  and  temperature.  The  data  obtained  from 
them  are  however  of  interest  in  comparison  with  the  frog  tadpole  results. 

The  experiments  will  be  taken  up  in  turn  beginning  with  the  series 
containing  the  largest  number  of  individuals  and  giving  the  most  uni- 
form results. 

Experiment    I      Rana   clamitans      Second   regenerations    of    the 
tail      Series  3676-3765 

The  tadpoles  were  collected  on  December  9,  1911  and  first  remov- 
als were  made  on  December  22  and  second  removals  on  January  8. 
Measurements  were  taken  4,  6,  8,  10,  12y2  and  56  days  after  the  opera- 
tion. The  operations  were  made  at  six  different  levels,  the  removals 
approximating  6,  10,  18,  31,  49  and  67  per  cent  of  the  tail  length.  The 
first  of  these  removals  averaged  1.5  mm.  and  four  individuals  with 
completed  measurements  are  available,  the  next  averaged  2.8  mm.  with 
seven  individuals,  the  third  4.9  mm.  with  five,  the  fourth  8.4  mm.  with 
ten,  the  fifth  13.1  mm.  with  eight  and  the  sixth  18.1  mm.  with  ten 
individuals.  The  rates  per  day  for  each  level  during  each  period  are 
given  in  table  55  and  in  graphic  form  in  figure  52.     The  maximum 


109] 


RATE  OF  REGENERATION— ZELENY 


109 


mm. 
0.20 

0.10 

0.20 
0.10 

0.20 
0.10 

0.30 
0.20 
0.10 


2        57      9    11%      15%  37 

— >-      Days  after  the  operation 
Figure  52     Rates  of  second  regenerations  of  the  tail  per  day  at  different  times 
after  the  operation  for  six  different  levels      Rana  clamitans      The  removed 
lengths  are  1.5,  2.8,  4.9,  8.4,  13.1  and  18.1  mm. 


110 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[110 


rate  is  reached  during  the  period  between  four  and  six  days  at  three 
of  the  levels  and  between  six  and  eight  days  at  the  other  three.  The 
rise  in  rate  is  very  rapid  and  the  decline  also  rapid. 

As  discussed  in  the  preceding  section  on  the  effect  of  the  level  of 
the  cut,  the  rate  of  regeneration  increases  with  depth  of  the  level  and 
the  increase  is  such  that  in  general  the  specific  length  or  length  regener- 
ated per  unit  of  removed  length  is  approximately  a  constant.  A  reduc- 
tion of  the  rates  to  specific  rates  therefore  gives  an  opportunity  for 
averaging  the  different  levels  together.  The  resultant  average  is  based 
upon  a  sufficiently  large  number  of  individuals  to  give  a  considerable 
degree  of  smoothness  in  the  curve  of  rate.     The  data  for  specific  rate 


2  nd 


5  7  9  11%  15% 

— >■      Days  after  the  operation 
Figure  53.     Specific  rates  of  first  and  second  regenerations  at  different  times 
after  the  operation        Rana  clamitans       Tail  regeneration      Upper  figure, 
second  regenerations;   lower,  first  regenerations. 

are  given  in  Table  56.  The  average  specific  rates  for  all  six  levels  to- 
gether are  0.019  mm.  during  the  0  to  4  day  period,  0.066  during  the 
4  to  6  day  period,  0.051  for  6  to  8  days,  0.033  for  8  to  10  days,  0.017  for 
10  to  12i/2  days,  0.001  for  12y2  to  18  days  and  —0.001  for  18  to  56 
days.  This  change  in  rate  is  represented  graphically  in  the  upper  part 
of  Figure  53.  For  the  four  deepest  levels  the  averages  are  given  in  a 
separate  column  of  Table  56.    They  exclude  the  two  lowest  levels  which 


Ill] 


RATE  OF  REGEXERATIOX—ZELENY 


111 


depart  considerably  from  the  others  in  specific  rate.  There  is  how- 
ever no  essential  difference  in  the  two  sets  of  values  as  regards  the  form 
of  the  rate  curve. 

The  change  in  rate  of  regeneration  or  acceleration  of  rate  from  any 
period  to  the  succeeding  one  is  shown  in  Table  57  in  which  the  period 
of  change  is  represented  by  the  middle  days  of  the  two  periods  which 
are  being  compared.  The  average  of  all  the  levels  shows  the  acceler- 
ation to  be  +0.095  mm.  from  the  2  to  the  5  day  period,  — 0.015  for  5  to 
7  days,  —0.030  for  7  to  9  days,  —0.058  for  9  to  11%  days,  —0.028  for 
11%  to  1514  days  and  — 0.001  for  15%  to  37  days.  It  is  only  between 
the  first  two  periods  that  acceleration  of  rate  is  a  plus  quantity.  Dur- 
ing all  the  others  it  is  minus,  the  most  rapid  rate  of  decrease  coming 
between  9  and  11%  days. 

The  accelerations  of  specific  rate  are  more  reliable  measures  for 
obtaining  averages  including  the  different  periods.  Such  values  are 
given  in  Table  58  and  in  graphic  form  in  Figure  54.  They  give  a  result 
in  the  relation  of  the  periods  to  each  other  essentially  similar  to  that 
above.     The  average  accelerations  of  specific  rate  are  -f 0.014  for  the 


6       8       10       13%  26 

— >■      Days  after  the  operation 
Figure  54 .    Acceleration  of  specific  rate     First  and  second  regenerations  of  the 
tail  in     Rana  clamitans    Unbroken  line=First  regeneration     Broken  line= 
Second  regeneration. 

2  to  5  day  periods,  — 0.004  for  5  to  7  days,  — 0.009  for  7  to  9  days, 
—0.0085  for  9  to  11%  days,  —0.003  for  11%  to  15%  days  and  0.000 
for  15%  to  37  days.  The  first  period  is  the  only  one  with  a  plus  accel- 
eration. The  greatest  minus  acceleration  comes  between  the  7  and  the 
9  day  periods  instead  of  9  to  11%  days.  Averaging  only  the  regener- 
ations for  the  four  deepest  levels  which  show  a  constant  specific  rate 


112 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[112 


the  values  are  respectively  +0.011,  0.000,  —0.005,  —0.006,  —0.004  and 
0.000,  putting  the  greatest  rate  of  decrease  between  the  9  and  the  11*4 
day  periods. 

An  examination  of  the  curves  of  specific  rate  and  a  comparison 
with  the  facts  of  histogenesis  shows  that  acceleration  of  rate  is  a  plus 
quantity  only  during  the  period  before  active  differentiation  of  the 
cells,  i.  e.  until  the  end  of  the  fifth  or  seventh  day.  As  soon  as  tissue 
differentiation  is  fairly  begun  the  retarding  influence  is  apparent  and 
by  the  ninth  to  eleventh  days  when  muscle  fibres  and  other  cells  are  in 
full  process  of  differentiation  the  negative  acceleration  is  at  its  height. 

Following  the  percentage  increment  method  used  by  Minot  (1908) 
for  ordinary  growth  and  using  length  instead  of  weight  because  the  latter 
could  not  be  determined  with  sufficient  accuracy  the  results  given  in 
Table  59  are  obtained.  The  values  for  the  six  periods  excluding  the  first 
one  are  106,  28,  12,  5  and  0.  The  regenerated  material  present  at  the 
end  of  four  days  is  made  up  almost  wholly  of  cells  that  have  migrated 
from  the  old  tissues  and  have  not  as  yet  undergone  division.  After  the 
fourth  day  the  additions  to  regenerated  material  are  almost  wholly 
the  result  of  cell  division.  From  the  end  of  the  fourth  to  the  end  of 
the  sixth  day  the  material  is  on  the  average  more  than  doubled  in  length 
each  day.  After  this  time  the  percentage  increment  decreases  rapidly. 
The  change  from  period  to  period  is  represented  in  graphic  form  in 
Figure  55.    The  curve  is  a  logarithmic  one  quite  similar  to  that  obtained 


eS 
•a 


9 
M 
eS 

4-> 

C 

9 
O 

$~ 
9 

a* 


100 


80 


60 


40 


20 


7  9  11*4  15% 

— ►■      Days  after  the  operation 
Figure  55     Percentage  increment  per  day  at  different  periods  after  the  opera- 
tion     First  and  second  regenerations  of  the  tail  of    Rana  clamitans      Un- 
broken line=first  regeneration.    Broken  line=second  regeneration. 


113] 


RATE  OF  REGENERATION —ZELENY 


113 


by  Minot  for  growth.  It  should  however  be  pointed  out  that  both 
regeueration  and  ordinary  growth  undoubtedly  have  a  very  rapidly 
ascending  branch  of  the  curve  if  the  very  beginnings  of  the  processes 
are  included. 

TABLE  55 

Rana  clamitans       Series  3676-3765       Second  regenerations 

Rate  of  regeneration  of  tail  per  day  at  different  times  during  the  regenerative 

process  for  six  different  levels 


Percent   of 

tail   length 

removed 

6 

10 

18 

31 

49 

67 

Length 
removed 
in   mm. 

1.5 

2.8 

4.9 

8.4 

13.1 

18.1 

No.    of    in- 
dividuals 

4 

7 

5 

10 

8 

10 

Days 

0-  4 

0.05 

0.10 

0.06 

0.10 

j       0.12 

0.13 

4-  6 

0.20* 

0.20* 

0.23 

0.34 

0.40 

0.91* 

6-  8 

0.14 

0.15 

0.25* 

0.35* 

0.50* 

0.70 

8-10 

0.05 

0.10 

0.10 

0.25 

0.50* 

0.70 

10-12% 

0.00 

0.00 

0.08 

0.12 

0.28 

0.44 

12Ms-18 

0.00 

—0.02 

—0.02 

0.00 

0.07 

0.15 

18-56 

0.00 

—0.01 

0.00 

0.00 

0.01 

000 

114 


ILLIXOIS  BIOLOGICAL   MONOGRAPHS 


[114 


TABLE  56 

Rana  clamitans       Series  3676-3765       Second  regenerations 
Specific  rates  at  different  levels  at  different  times 


Percent  of 

tail  length 

removed 

6 

10 

18 

31 

49 

67 

Average 

of 

all 

levels 

Length 
removed 
in  mm. 

1.5 

2.8  * 

4.9 

8.4 

13.1 

18.1 

Average 
of  four 
longest 
remov- 

No. of  in- 
dividuals 

4 

7 

5 

10 

8 

10 

als.  . 

Days 
0-  4 

0.037 

0.Q35 

0.012 

0.012 

0.010 

0.007 

0.019 

0.010 

4-  6 

0.135* 

0.080* 

0.045 

0.040 

0.045* 

0.050* 

0.066* 

0.045* 

8-10 

0.035 

0.035 

0.025 

0.030 

0.035 

0.035 

0.051 

0.042 

6-  8 

0.090 

0.045 

0.050* 

0.045* 

0.040 

0.040 

0.033 

0.032 

10-12% 

0.000 

0.000 

0.025 

0.015 

0.030 

0.030 

0.017 

0.025 

12%-18 

0.000 

—0.005 

—0.004 

0.000 

0.005 

0.009 

0.001 

0.002 

18-56 

—0.002 

—0.004 

0.001 

0.000 

0.001 

0.000 

—0.001 

0.000 

115] 


RATE  OF  REGENERATION— ZELENY 


115 


TABLE  57 

Rana  clamitans       Series  3676-3765       Second  regenerations 
Acceleration  of  rate  of  regeneration  of  tail  per  day  at  different  times  during 
the  regenerative  process  for  six  different  levels 


Percent   of 

tail    length 

removed 

6 

10 

Length 

removed 

in  mm. 

1.5 

2.8 

No.  of  in- 
dividuals 

4 

7 

Middle  of 

periods 

Days 

2-  5 

+0.05* 

+0.03* 

5-  7 

—0.03 

—0.02 

7-  9 

—0.04* 

—0.02 

9-11% 

—0.02 

—0.04* 

11%-15% 

0.00 

—0.00 

15^-37 

—0.00 

—0.00 

18 


4.9 


+0.06* 


+0.01 


-0.07* 


-0.01 


-0.02 


+0.00 


31 


8.4 


10 


+  0.08* 


+0.00 


—0.05 


—0.06* 


—0.03 


-0.00 


49 


13.1 


+0.09* 


+0.05 


0.00 


-0.10s1 


—0.05 


—0.00 


67 


18.1 


10 


+0.26* 


—0.10 


0.00 


—0.12* 


—0.07 


-0.01 


Average 

of 

all 

levels 


+0.095* 


.015 


—0.030 


—0.058* 


—0.028 


.001 


116 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[116 


TABLE  58 
Rana  clamitans      Series  3676-3765      First  regenerations 
Acceleration  of  specific  rate  of  regeneration  of  the  tail 


Percent  of 

tail 

length 

removed 

6 

10 

18 

31 

49 

67, 

Average 
of     . 
all 
levels 

Average 

of  four 

deepest 

levels 

Length 
removed 
In  mm. 

1.5 

2.8 

4.9 

8.4 

13.1 

18.1 

No.  of  in- 
dividuals 

4 

7 

5 

10 

8 

10 

Days 
2-  5 

+0.033* 

+0.011* 

+0.012* 

+0.010* 

+0.007* 

•fO.014* 

+0.014* 

+0.011* 

5-  7 

—0.020 

—0.007 

+0.002 

0.000 

+0.004 

—0.006 

—0.004 

0.000 

7-  9 

—0.027* 

—0.007 

—0.014* 

—0.006 

0.000 

0.000 

—0.009* 

—0.005 

9-11% 

—0.013 

—0.014* 

—0.002 

—0.007* 

—0.008* 

—0.007 

—0.008 

—0.006* 

11*4-15% 

0.000 

0.000 

—0.004 

—0.004 

—0.004 

—0.004 

—0.003 

—0.004 

15*4-37 

0.000 

0.000 

0.000 

0.000 

0.000 

—0.001 

0.000 

0.000 

117] 


RATE  OF  REGENERATION— ZELENY 


117 


TABLE  59 

Rana  clamitans       Series  3676-3765       First  regenerations 

Percentage  increment  of  regenerating  tail  per  day  during  each  time  period  for 

six  different  levels 


Percent   of 

tail   length 

removed 

6 

10 

18 

31 

49 

67 

Average 

of 

all 

levels 

Length 
removed 
in  mm. 

1.5 

2.8 

4.9 

8.4 

13.1 

18.1 

No.  of  in- 
dividuals 

4 

7 

5 

10 

8 

10 

Days 
4-  6 

91 

53 

96 

142 

80 

175 

106 

6-  8 

23 

19 

36 

32 

29 

30 

28 

8-10 

5 

9 

8 

14 

19 

19 

12 

10-12^ 

0 

0 

6 

5 

8 

9 

5 

12%-18 

0 

—2 

—1 

0 

2 

2 

0 

18-56 

—0 

—1 

+0 

—0 

+0     ( 

+0 

0 

118  ILLINOIS  BIOLOGICAL   MONOGRAPHS  [118 

Experiment  II     Rana  clamitans     First  regenerations  of  the  tail 

Series  3676-3765 

The  tadpoles  were  collected  on  December  9,  1911,  and  the  tail  remov- 
als were  made  on  January  8.  Measurements  were  taken  4,  6,  8,  10,  12^2, 
18  and  56  days  after  the  operations.  The  operations  were  at  six  levels 
approximating  6,  10,  17,  30,  48  and  62  per  cent  of  the  original  tail 
length.  For  the  first  of  these  levels  only  two  individuals  with  an  average 
removal  of  1.5  mm.  are  available,  for  the  second  five  individuals  with 
2.6  mm.,  for  the  third  three  with  4.6  mm.,  for  the  fourth  eight  with  8.2 
mm.,  for  the  fifth  five  with  13.0  mm.  and  for  the  sixth  five  with  16.7  mm. 
The  rates  of  regeneration  per  day  are  given  in  table  60  and  the  graphs 
for  the  rates  in  Figure  56. 

The  specific  rates  are  given  in  Table  61.  Averaging  these  values 
so  as  to  include  all  the  different  levels  for  each  period  the  specific  rates 
are  0.018  for  0  to  4  days,  0.046  for  4  to  6  days,  0.057  for  6  to  8  days, 
0.037  for  8  to  10  days,  0.026  for  10  to  12y2  days,  0.002  for  12i/2  to  18 
days  and  — 0.001  for  18  to  56  days.  The  graph  is  shown  in  the  unbroken 
line  in  Figure  53.  Using  only  the  four  deepest  levels  the  average  specific 
rates  are  respectively  0.013,  0.042,  0.045,  0.036,  0.025,  0.006  and  0.000 
giving  essentially  the  same  form  of  curve  as  for  the  average  of  all  levels. 

The  accelerations  of  rate  are  shown  in  Table  62  and  the  accelerations 
of  specific  rate  in  Table  63  and  in  the  unbroken  line  of  Figure  54.  The 
average  accelerations  of  rate  per  day  are  respectively  -j-0.078,  0.000, 
—0.022,  —0.042,  —0.025  and  0.000  mm.  The  average  accelerations  of 
specific  rate  including  all  levels  are  respectively  -4-0.011,  — 0.001, 
—0.007,  —0.0075,  —0.003  and  0.000  and  including  only  the  four  deepest 
levels,  4-0.009,  0.000.  —0.004,  —0.005,  —0.003  and  0.000.  As  for  sec- 
ond regenerations  the  only  plus  acceleration  is  between  2  and  5  days 
and  the  most  rapid  decrease  takes  place  between  9  and  lli/4  days. 

The  percentage  increments  per  day  are  shown  in  Table  64  and  in  the 
unbroken  line  of  Figure  55.  The  values  are  respectively  98,  29,  17,  6, 
1  and  0  percent  per  day  giving  approximately  the  same  form  of  curve 
as  for  second  regenerations. 

In  general  the  first  regenerations  agree  with  the  second  but  on  the 
whole  the  second  regenerations  reach  their  maximum  earlier  and  are 
more  rapid  than  the  first  up  to  the  time  of  maximum  rate.  The  first 
are  more  rapid  than  the  second  after  the  maximum. 


119] 


RATE  OF  REGENERATIOS —ZELENY 


119 


2  5      7     9     11%      15% 

— >      Days  after  the  operation 
Figure  56      Rates  of  first  regenerations  of  the  tail  per  day  at  different  times 
after  the  operation  for  six  different  levels       Rana  clamitans     The  removed 
lengths  are  1.5,  2.6,  4.6,  8.2,  13.0  and  16.7  mm. 


120 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[120 


TABLE  60 

Rana  clamitans       Series  3676-3765       First  regenerations 

Rate  of  regeneration  of  tail  per  day  at  different  times  during  the  regenerative 

process  for  six  different  levels 


Percent  of 

tail  length 

removed 

6 

10 

17 

30 

48 

62 

Length 

removed  in 

mm. 

1.5 

2.6 

4.6 

8.2 

13.0 

16.7 

No.  of 
individuals 

2 

5 

3 

8 

5 

5 

Days 

0-  4 

0.07 

0.02 

0.12 

0.10 

0.12 

0.12 

4-  6 

0.10 

0.20* 

0.25* 

0.35* 

0.55* 

0.55 

6-  8 

0.15* 

0.10 

0.25* 

0.30 

0.50 

0.70 

8-10 

0.05 

0.15 

0.10 

0.30 

0.40 

0.75* 

I 
10-12% 

0.00 

0.08 

0.04 

0.12 

0.36 

0.52 

12%-18 

0.00 

—0.02 

0.00 

0.02 

0.15 

0.18 

18-56 

-0.01 

0.00 

—0.01 

—0.01 

0.00 

0.00 

121] 


RATE  OF  REGENERATION— ZELENY 


121 


TABLE  61. 
Rana  clamitans      Series  3676-3765      Second  regenerations 
Specific  rates  at  different  levels  at  different  times 


Percent  of 

tail  length 

removed 

6 

10 

17 

30 

Length 
removed 
in  mm. 

1.5 

2.6 

4.6 

8.2 

No.  of  in- 
dividuals 

2 

5 

3 

8 

Days 
0-  4 

0.042 

0.015 

0.027 

0.012 

4-  6 

0.065 

0.040 

0.055* 

0.040* 

6-  8 

0.115* 

0.045 

0.055* 

0.040* 

8-10 

0.025 
0.015 

0.055* 

0.020 

0.035 

10-12% 

0.040 

0.010 

0.015 

12%-18 

—0.002 

—0.007 

0.000 

0.004 

18-56 

—0.004 

—0.001 

—0.001 

—0.001 

48 


13.0 


0.000 


62 


16.7 


5 



5 

0.007 

« 

0.007 

0.045* 

0.030 

0.040 

0.045* 

0.045* 

0.045* 

0.035 

0.040 

0.011 

0.009 

0.000 


—0.001 


Average 

of 

all 

levels 

Average 
of  four 
longest 
remov- 
als 

0.018 

0.013 

0.046 

0.042 

0.057* 

0-045* 

0.037 

0.036 

0.026 

0.025 

0.002 

0.006 

0.000 


122 


ILLIX01S   BIOLOGICAL   MOXOGRAPHS 


[122 


TABLE  62 

Rana  clamitans       Series  3676-3765       First  regenerations 

Acceleration  of  rate  of  regeneration  of  tail  per  day  at  different  times  during  the 

regenerative  process  for  six  different  levels 


Percent  of 

tail  length 

removed 

6 

10 

17 

30 

48 

62 

Average 

of 

all 

levels 

Length    re- 
moved in 
mm. 

1.5 

2.6 

4.6 

8.2 

13.0 

16.7 

No.  of  in- 
dividuals 

2 

5 

3 

8 

5 

5 

Middle  of 

periods 

Days. 

2-  5 

+0.01 

+0.06* 

+  0.04* 

+  0.08* 

+0.14* 

+0.14* 

+0.078* 

5-  7 

+0.02* 

—0.05* 

0.00 

—0.02 

—0.02 

+0.07 

0.000 

7-  9 

—0.05* 

+0.02 

—0.07* 

0.00 

—0.05* 

+0.02 

—0.022 

9-11% 

—0.02 

—0.03 

—0.02 

—0.07* 

—0.02 

—0.09* 

—0-042* 

ll^-lo^i 

0.00 

-0.02 

—0.01 

—0.02 

—0.04 

—0.06 

—0.025 . 

15%-37 

—0.00 

0.00 

—0.00 

—0.00 

0.00 

+0.00 

-O.000 

123] 


RATE  OF  REGENERATION— ZELENY 


123 


TABLE   63 

Rana  clamitans       Series  3676-3765       First  regenerations 
Acceleration  of  specific  rate  of  regeneration  of  the  tail 


Percent  of 

tail 

length 

removed 

6 

10 

18 

31 

49 

67 

Average 
of     . 
all 
levels 

Average 

of  four 

deepest 

levels 

Length 
removed 
in  mm. 

1.5 

2.8 

4.9 

8.4 

13.1 

18.1 

No.  of  in- 
dividuals 

4 

7 

5 

10 

8 

10 

Days 
2-  5 

4-0.007 

+0.023* 

f0.009* 

+0.010* 

-fO.011* 

+  0.008* 

-1-0.011* 

+0.009* 

5-  7 

f0.013* 

—0.019* 

0.000 

—0.002 

-0.002 

+0.004 

—0.001 

0.000 

7-  9 

—0.033* 

-1-0.008 

—0.015* 

0.000 

—0.004* 

+0.001 

—0.007 

—0.004 

9-11% 

—0.013 

—0.012 

—0.004 
—0.002 

—0.009* 

—0.002 

—0.005* 

—0.007* 

—0.005* 

11^-15% 

0.000 

—0.008 

—0.002 

—0.003 

-0.004 

—0.003 

—0.003 

15^-37 

0.000 

0.000 

0.000 

0.000 

0.000 

0.000 

0.000 

0.000 

124 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[124 


TABLE  64 

Rana  clamitans       Series  3676-3765      First  regenerations 

Percentage  increment  of  regenerating  tail  per  day  during  each  time  period 

for  six  different  levels 


Percent   of 

tail    length 

removed 

6 

10 

17 

30 

48 

62 

Average 

of 

all 

levels 

Length    re- 
moved in 
mm. 

1.5 

2.6 

4.6 

8.2 

13.0 

16.7 

No.  of  in- 
dividuals 

2 

5 

3 

8 

5 

5 

Days 
4-  6 

33 

200 

50 

87 

110 

110 

"  98 

6-  8 

30 

20 

25 

27 

31 

44 

29 

8-10 

6 

21 

7 

18 

23 

25 

17 

10-12% 

0 

8 

2 

5 

9 

12 

6 

12%-18 

'    0 

—2 

0 

1 

3 

3 

1 

18-56 

.  —0 

0 

—0   " 

—0 

0 

+0 

0 

Experiment  III      Rana  clamitans    .  First  and  second  regenerations 
op  the  tail.      Series  3628-3675 

For  comparison  with  the  data  of  experiments  I  and  II  it  is  of 
interest  to  note  the  results  obtained  from  this  entirely  different 
series  of  the  same  species  which  was  designed  primarily  for  the 
comparison  of  first  and  second  regenerations.  A  full  description  of  the 
experiment  is  given  in  the  section  on  the  effect  of  successive  removal 
upon  the  rate  of  regeneration.  The  data  of  specific  value  for  present 
purposes  are  given  in  Table  65.  Measurements  were  made  only  at  six 
and  at  eight  days  after  the  operation.  Fifty  percent  in  length  of  the 
tail  was  removed  in  both  first  and  second  regenerations.  Twenty-  one 
individuals  are  available  for  first  and  sixteen  for  second  regenerations. 

The  rates  per  day  are  0.52  mm.  for  6  to  8  days  for  first  regener- 
ations as  compared  with  0.50  for  the  same  period  in  Experiment  II  and 
0.62  for  second  regenerations  as  compared  with  0.50  in  Experiment  I. 
The  specific  rate  per  day  for  6  to  8  days  for  first  regenerations  is  0.049 


125] 


RATE   OF  REGENERATION— ZELENY 


125 


and  for  second  regenerations  0.057  as  compared  with  0.050  for  forty 
eight  percent  removals  in  the  first  regenerations  of  Experiment  II  and 
0.050  for  forty  nine  percent  removals  in  the  second  regenerations  of 
Experiment  I. 

The  percentage  increments  per  day  are  26  for  first  regenerations 
as  compared  with  29  in  Experiment  II  and  28  for  second  regenerations 
as  compared  with  28  in  Experiment  I. 

The  close  agreement  of  these  values  taken  from  a  comparatively 
large  number  of  individuals  strengthens  the  conclusion  as  to  the  validity 
of  the  comparisons  at  different  periods  and  levels  in  experiments  I  and  II. 

TABLE   65 

Rana  clamitans       Series  3628-3765 

First  and  second  regenerations  of  the  tail      Six  and  eight  days 


No.  of 
individ- 
uals 

Total 

length 

mm. 

Tail 

length 
mm. 

Percent 

of 

length 

re- 
moved 

Length 

re- 
moved 

Regen- 
erated 
length 
Six 
days 

Regen-i 

erated 

length 

Eight 

days 

Rate 
per 
day 

Spe- 
cific 
rate 

Percent- 
age in- 
crement 

per 

day 

First 
regeneration 

21 

32.7 

21.4 

50 

10.6 

2.01 

3.06 

0.52 

0.049 

26 

Second 
regeneration 

16 

33.4 

21.8 

50 

10.9 

2.18 

3.42 

0.64 

0.057 

28 

Experiment  IV     Amblystoma  punctatum     Tail      Series  4600-5052 

Operations  were  made  at  five  levels  approximating  10,  21,  34,  53  and 
74  per  cent  of  the  original  tail  length.     The  removed  lengths  average 
respectively  1.1,  2.2,  3.7,  5.8  and  8.1  mm.     Measurements  were  made 
2,  4,  6,  8-9,  10-11,  13,  14-15  and  16-17  days  after  the  operation.     The 
rates  per  day  for  each  of  the  levels  at  each  of  the  different  times  are 
given  in  Table  66. 

The  specific  rates  are  shown  in  Table  67.  The  averages  for  all  the 
levels  at  each  of  the  time  periods  are  respectively  0.032  mm.  for  0  to  2 
days,  0.004  for  2  to  4  days,  0.053  for  4  to  6  days,  0.039  for  6  to  8  days, 
0.064  for  8.4  to  10.3  days,  0.043  for  10.3  to  13.0  days,  0.012  for  13.0 
to  15.2  days  and  0.019  for  15.2  to  17.3  days.  As  in  the  case  of  other 
salamander  experiments  the  data  are  more  irregular  than  those  for  the 
frog  tadpoles  because  of  the  susceptibility  of  the  salamander  larvae 
to  factors  which  have  not  so  far  been  brought  under  control.  The 
character  of  the  food  is  probably  an  important  factor.  The  greatest 
rate  comes  between  8.4  and  10.3  days  after  the  operation  for  three  of 
the  five  levels  and  also  for  the  average  of  all  levels.    This  is  later  than 


126 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[126 


the  maximum  for  the  frog  tadpole  which  comes  between  four  and  six 
days  for  second  regenerations  and  between  six  and  eight  days  for 
first  regenerations.  The  period  of  decline  in  rate  is  also  more  extended 
in  these  salamander  larvae  than  in  the  frog  tadpoles  of  Experiments 
I  and  II. 

On  account  of  the  irregularity  of  the  data  it  is  not  possible  to 
study  the  acceleration  of  rate  for  the  present  data. 

The  percentage  increments  per  day  are  given  in  Table  68.  The 
values  for  the  seven  time  periods  are  respectively  8,  71,  20,  23,  14,  4 
and  7.  The  greatest  percentage  increment  comes  between  4  and  6 
days  as  in  the  case  of  the  frog  tadpoles.  An  earlier  period,  that  be- 
tween two  and  four  days  is  represented  here.  During  this  period 
the  percentage  increment  is  low.  If  this  value  can  be  accepted  the 
curve  here  includes  the  very  steep  ascending  portion  discussed  above. 
The  irregularities  in  rate  to  which  the  salamander  larvae  are  subject 
and  the  fact  that  the  low  value  during  this  period  does  not  appear  in 
all  the  salamander  experiments  however  makes  the  interpretation 
doubtful. 

TABLE  66 
Amblystoma  punctatum  Series  4600-5052 

Rate  of  regeneration  of  tail  per  day  at  different  times  during  the  regenerative 
process  for  five  different  levels 


Percent  of  tail  , 
removed 

10 

21 

34 

53 

74 

Length  removed, 
in  mm. 

1.1 

2.2 

3.7 

.5.8 

8.1 

Days 
0-2 

0.05 

0.07 

0.07 

0.23 

0.26 

2-4 

0.01 

0.00 

0.07 

—0.03 

—0.06 

4-6 

0.10* 

0.16 

0.16 

0.14 

0.27 

6-8.4 

0.03 

0.07 

0.07 

0.29 

0.21 

8.4-10.3 

0.05 

—0.01 

0.39* 

0.43 

0.37 

10.3-13.0 

0.10* 

0.11 

0.07 

0.07 

0.51* 

13.0-15.2 

0.01 

0.17* 

—0.17 

0.18 

0.09 

15.2-17.3 

—0.05 

0.05 

0.11 

0.48* 

0.41 

127] 


RATE  OF  REGENERATION— ZELENY 


127 


TABLE  67 

Amblystoma  punctatum         Series  4600-5052 

Specific  rates  of  regeneration  of  the  tail  at  different  levels  at  different  times 

after  the  operation 


Percent  of  tail 
removed 

10 

21 

34 

53 

74 

Average 
of  all 
levels 

Length   re- 
moved in  mm. 

1.1 

2.2 

3.7 

5.8 

8.1 

Days 
0-2 

0.035 

0.035 

0.020 

0.040 

0.030 

0.032 

2-4 

0.020 

—0.005 

0.015 

—0.005 

—0.005 

0.004 

4-6 

0.095 

0.070 

0.045 

0.025 

0.030 

0.053 

6-8.4 

0.054 

0.033 

0.029 

0.046 

0.033 

0.039 

8.4-10.3 

0.100* 

—0.011 

0.105* 

0.095* 

0.042 

0.064* 

10.3-13.0 

0.044 

0.063 

0.019 

0.011 

0.078* 

0.043 

13.0-15.2 

—0.032 

0.081* 

—0.036 

0.018 

0.027 

0.012 

15.2-17.3 

0.000 

0.005 

0  005 

0.069 

0.014 

0.019 

128 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[128 


TABLE  68 

Amblystoma  punctatum         Series  4600-5052 

Percentage  increment  of  regenerating  tail  per  day  during  each  time  period  for 

five  different  levels 


Percent  of  tail 
removed 

10 

21 

34 

53 

74 

Average 

of  all 

.levels 

Length   re- 
moved in  mm. 

1.1 

2.2 

3.7 

5.8 

8.1 

Days 
2-4 

10 

0 

50 

—6 

—12 

8 

4-6 

83* 

107* 

53* 

35 

77* 

71* 

6-8.4 

10 

16 

12 

42* 

20 

20 

8.4-10.3 

13 

—2 

49 

31 

24 

23 

10.3-13.0 

27 

17 

5 

3 

23 

14 

13.0-15.2 

1 

19 

—10 

8 

3 

4 

15.2-17.3 

—6 

4 

8 

17 

11 

7 

Experiment  V      Amblystoma  punctatum      Tail      Series  4101-4540 

The  experiment  consists  of  the  regenerations  of  removed  halves  of  the 
tail  without  additional  injury  in  some  individuals  and  with  an  additional 
removal  of  the  two  forelegs  in  others.  Measurements  were  made  at  nine 
periods,  2,  4,  6,  8, 10, 12, 14, 16  and  19  days  after  the  operation.  The  rates 
of  regeneration  are  given  in  Table  69.  The  number  of  individuals  for  most 
of  the  levels  is  five.  The  full  data  are  discussed  in  the  section  on  the 
effect  of  degree  of  injury.  The  average  rate  for  each  of  the  different 
times  shows  that  the  maximum  comes  during  the  eight  to  ten  day  period. 
The  high  value  for  the  greater  degree  of  injury  at  14  to  16  days  is 
due  to  the  death  during  that  period  of  the  two  individuals  with  the 
lowest  values.  The  result  agrees  very  well  with  the  maximum  rate  in 
Experiment  IV. 

The  percentage  increments  are  given  in  Table  70.  The  highest 
value  comes  during  the  two  to  four  day  period  followed  by  decrease 
with  but  little  irregularity. 


129] 


RATE  OF  REGENERATION— ZELENY 


129 


Experiment  VI     Amblystoma  punctatum     Tail     Series  3962-4004 

First,  second  and  third  regenerations  after  removal  of  approximately 
one-half  of  the  tail  were  studied.  The  complete  data  are  given  in  the 
section  on  the  effect  of  successive  removals.  Measurements  were  made  at 
2,  4,  6,  8,  10  and  14  days.  The  rates  per  day  are  given  in  Table  71.  The 
maximum  rate  comes  between  8  and  10  days  agreeing  with  the  other  data 
for  regeneration  of  the  tail  in  salamander  larvae. 

The  percentage  increments  are  given  in  Table  72.  The  highest 
rate  comes  at  the  earliest  period,  between  two  and  four  days,  and  is 
followed  by  a  rapid  and  then  a  slower  decrease. 


TABLE  69 
Amblystoma  punctatum      Series  4101-4540 
Rate  of  regeneration  per  day  of  tail  at  different  times  during  the  regenerative 
process  for  two  degrees  of  injury 


Period 
of 
regeneration 
Days 


0-2 


2-4 


4-6 


6-8 


8-10 


10-12 


12-14 


14-16 


16-19 


Middle  of 

period 
Days  after 
operation 


11 


13 


15 


17% 


Rate  of  regeneration  per 
day  for  each  period 


One-half 
tail 


0.17 


0.19 


0.29 


0.37 


0.69* 


0.46 


0.23 


0.37 


0.16 


One-half 

tail  .+ 

fore-legs 


0.13 


0.27 


0.25 


0.47 


0.50 


0.46 


0.37 


0.53* 


0.03 


Average 
rate 


0.15 

0.23 

0.27 

0.42 

0.59* 

0.46 

0.30 

0.45 

0.09 


130 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[130 


TABLE  70 

Amblystoma  punctatum  Series  4101-4540 

Percentage  increment  per  day  of  regenerating  tail  at  different  times  during  the 

regenerative  process  for  two  degrees  of  injury 


Days 

Percentage  increment  per 
day  during  each  period 

Average 

One-half  tail 

One-half  tail+ 
fore-legs 

2  to  4 

54* 

100* 

77 

4  to  6 

40 

31 

35 

6  to  8 

28 

36 

32 

8  to  10 

33 

22 

27 

10  to  12 

13 

14 

13 

12  to  14 

5 

9 

7 

14  to  16 

8 

11 

9 

16  to  '19 

3 

0 

1 

TABLE  71 

Amblystoma  punctatum     Series  4101-4540 

Rate  of  regeneration  per  day  at  different  times  during  the  regenerative  process 


Period 

of 

regeneration 

Days 

Middle 
of  period 
Days  after 
operation 

Rate  of  regeneration  per  day 
during  each  period 

Average 

First 

Second 

Third 

0-2 

1 

0.11 

0.12 

0.13 

0.12 

2-4 

3 

0.22 

0.25 

0.37 

0.28 

4-6 

5 

0.35 

0.32 

0.18 

0.28 

6-8 

7 

0.41 

0.64* 

0.66 

0.57 

8-10 

9 

0.68* 

0.57 

0.76* 

0.67* 

10-14 

12 

0.45 

0.57 

0.47 

0.50 

131] 


RATE  OF  REGENERATION —ZELENY 


131 


TABLE  72 

Amblystoma  punctatum     Series  3962-4004 

Percentage  increment  per  day  at  different  times  during  the  regenerative  process 


Days 

Percentage  increment  per  day  during 
each  period 

Average 

First 

Second 

Third 

2  to  4 

100 

100 

142 

114* 

4  to  6 

53 

43 

18 

38 

6  to  8 

30 

45 

48 

41 

8  to  10 

31 

21 

28 

27 

10  to  14 

12 

15 

11 

13 

Experiment  VII 


Amblystoma  punctatum 
Series  4101-4540 


Forelegs 


The  experiment  consists  of  the  study  of  the  rate  of  regeneration 
of  single  completely  removed  fore-legs  under  three  degrees  of  injury 
to  the  individual :  without  additional  injury,  with  the  other  fore-leg  re- 
moved at  the  same  time  and  with  the  other  fore-leg  plus  one-half  of  the 
tail  removed  .  Measurements  were  made  at  2,  4,  6,  8,  10,  12,  14,  16  and 
19  days.  The  rates  of  regeneration  are  given  in  Table  73.  The  maxi- 
mum rate  does  not  come  until  the  14  to  16  period.  The  percentage 
increments  are  given  in  Table  74.  The  highest  value  comes  during  the 
2  to  4  day  period.    There  is  a  gradual  decrease  from  this  time. 

On   the  whole  the   data  for  the  leg  regeneration  show  a  more 
extended  period  than  do  the  tail  regenerations^ 


132 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[132 


TABLE  73 
Amblystoma  punctatum      Series  4101-4540 
Rate  of  regeneration  per  day  of  fore-leg  at  different  times  during  the  regener- 
ative process   for  three   degrees   of  injury 


Period 

of 

regeneration 

Days 

Middle 

of 

period 

Days  after 

operation 

Rate  of  regeneration  per  day 
for  each  period 

Average 

One 
fore-leg 

Both 
fore-legs 

Both  fore- 
legs + 
one-half  tail 

0-2 

1 

0.06 

0.08 

0.07 

0.07 

2-4 

3 

0.04 

0.10 

0.07 

0.07 

4-6 

5 

0.10 

0.08 

0.13 

0.10 

6-8 

7 

0.12 

0.15 

0.09 

0.12 

8-10 

9 

0.12 

0.25 

0.25 

0.21 

10-12 

11 

0.28 

0.18 

0.18 

0.21 

12-14 

13 

0.25 

0.29 

0.34 

0.29 

14-16 

15 

0.52* 

0.41* 

0.39* 

0.44* 

16-19 

17% 

0.27 

0.21 

0.27 

0.25 

133] 


RATE  OF  REGENERATION— ZELENY 


133 


TABLE  74 

Amblystoma  punctatum     Series  4101-4540 

Percentage  increment  per  day  of  regenerating  fore-leg  at  different  periods  for 

three  degrees  of  injury 


Days 

Percentage  increment  per  day 
during  each  period 

Average 

One 
fore-leg 

Two 

fore-legs 

Both  fore- 
legs + 
one-half 
tail 

2-4 

34 

62* 

46* 

47* 

4-6 

45* 

23 

45 

38 

6-8 

28 

28 

16 

24 

8-10 

19 

30 

35 

28 

10-12 

31 

9 

15 

18 

12-14 

17 

18 

21 

19 

14-16 

26 

19 

17 

21 

16-19 

14 

10 

13 

12 

Discussion 

The  results  obtained  from  the  present  study  show  that  with  certain 
material  it  is  possible  to  control  disturbing  factors  so  as  to  get  data  of 
a  sufficiently  uniform  nature  for  an  analysis  of  the  change  in  rate.  Such 
material  was  found  in  the  tails  of  the  tadpoles  of  Rana  clamitans.  The 
analysis  has  yielded  results  which  should  be  of  value  in  a  determination 
of  the  factors  involved  in  the  stimulation  of  growth  and  more  particu- 
larly those  concerned  in  slowing  it  down  and  finally  bringing  it  to  a  stop. 
The  characteristics  of  the  change  in  rate  have  been  studied  by  means  of 
the  curves  of  rate,  of  acceleration  of  rate  and  of  percentage  increments. 
The  rate  is  slow  at  first,  increases  rapidly  until  it  is  near  a  maximum  at 
about  eight  days;  then  decreases,  at  first  rapidly  and  then  more  and 
more  slowly  as  zero  is  approached.  The  acceleration  of  rate  is  plus  only 
between  the  first  two  periods,  i.  e.,  up  to  the  fifth  day.  After  that  it  is 
minus,  reaching  its  lowest  point  at  ten  days.    The  percentage  increment 


134  ILLINOIS  BIOLOGICAL   MONOGRAPHS  [134 

is  very  high  between  the  first  and  second  periods  but  decreases  very 
rapidly  at  first  and  then  more  slowly. 

It  is  evident  that  there  is  a  close  similarity  between  the  change  in 
rate  of  growth  during  the  regeneration  cycle  and  the  change  in  rate 
during  an  ordinary  developmental  cycle  and  there  is  every  reason  to 
believe  that  the  factors  controlling  the  one  are  similar  to  those  controlling 
the  other.  The  problem  of  the  factors  is  particularly  interesting  when 
it  is  noted  that  for  widely  different  levels  the  rates  of  regeneration  differ 
in  such  a  way  that  length  regenerated  in  a  given  time  is  proportional  to 
the  length  removed.  The  process  of  regeneration  apparently  is  initiated 
in  a  similar  manner  at  each  level  but  is  kept  under  such  control  that  only 
a  certain  per  cent  of  the  length  is  regenerated  in  a  given  time. 

Knowledge  of  the  process  is  at  present  insufficient  to  enable  one 
to  discuss  with  profit  the  nature  of  the  control  of  rate  of  regeneration. 
All  that  can  be  done  is  to  point  out  the  relations  of  certain  phenomena. 
The  initial  slow  period  is  coincident  with  the  period  of  cell  migration 
without  cell  division,  the  period  of  rapidly  increasing  rate  is  coincident 
with  the  period  of  rapid  cell  multiplication  without  pronounced  cell 
differentiation  and  the  period  of  rapidly  decreasing  rate  is  associated 
with  the  appearance  of  pronounced  differentiation  in  the  cells.  There  is 
certainly  some  causal  relation  between  these  phenomena. 

Summary 

1.  In  second  regenerations  of  the  tail  in  Rana  clamitans  the  average 
specific  rates  are  0.019  mm.  for  the  0  to  4  day  period,  0.066  for  the  4  to  6 
day  period,  0.051  for  6  to  8  days,  0.033  for  8  to  10  days,  0.017  for  10 
to  12y2  days,  0.001  for  12y2  to  18  days  and  —0.001  for  18  to  56  days. 

2.  The  average  accelerations  of  rate  are  -f-0.095  mm.  per  day  from 
the  first  to  the  second  period,  — 0.015  from  the  second  to  the  third, 
—0.030  from  the  third  to  the  fourth,  —0.058  from  the  fourth  to  the  fifth, 
— 0.028  from  the  fifth  to  the  sixth  and  — 0.001  from  the  sixth  to  the 
seventh. 

3.  The  average  percentage  increments  between  the  same  periods 
are  respectively  106,  28,  12,  5,  0  and  0. 

4.  The  average  accelerations  of  specific  rate  for  the  four  deepest 
levels  between  the  same  periods  are  respectively  -4-0.011  mm.,  0.000, 
—0.005,  —0.006,  —0.004  and  0.000. 

5.  In  first  regenerations  of  the  tail  in  Rana  clamitans  the  average 
specific  rates  are  0.018  mm.  for  0  to  4  days,  0.046  for  4  to  6  days,  0.057 
for  6  to  8  days,  0.037  for  8  to  10  days,  0.026  for  10  to  12y2  days,  0.002 
for  12y2  to  18  days  and  —0.001  for  18  to  56  days. 

6.  The  average  accelerations  of  rate  are  +0.078  mm.  per  day  from 


135]  RATE  OF  REGENERATION— ZELENY  135 

the  first  to  the  second  period,  0.000  from  the  second  to  the  third,  — 0.022 
from  the  third  to  the  fourth,  —0.042  from  the  fourth  to  the  fifth,  —0.025 
from  the  fifth  to  the  sixth  and  0.000  from  the  sixth  to  the  seventh. 

7.  The  average  accelerations  of  specific  rate  for  the  four  deepest 
levels  between  the  same  periods  are  respectively  +0.009,  0.000,  — 0.004, 
—0.005,  —0.003  and  0.000. 

8.  The  average  percentage  increments  between  the  same  periods  are 
respectively  98,  29,  17,  6,  1  and  0. 

9.  The  experiments  on  salamander  larvae  show  a  similar  change  in 
rate  of  regeneration  during  the  process  but  the  number  of  individuals 
is  too  small  to  allow  an  analysis  of  the  data. 

10.  The  changes  in  rate  that  have  been  noted  bear  a  definite  relation 
to  the  histological  changes  that  have  been  observed  during  the  regener- 
ation of  the  tail. 


136  ILLINOIS  BIOLOGICAL   MONOGRAPHS  [136 


PART  V 

THE  EFFECT  OF  DEGREE  OF  INJURY  UPON  THE  RATE  OF 

REGENERATION 

In  a  former  series  of  papers  the  writer  gave  the  results  of  experi- 
ments on  the  effect  of  degree  of  injury  upon  the  rate  of  regeneration.  A 
number  of  different  species  of  animals  and  various  combinations  of 
injuries  were  involved.  The  results  then  obtained  tend  on  the  whole 
to  show  that  within  certain  limits  the  rate  of  regeneration  from  an 
injured  surface  is  not  retarded  by  simultaneous  regeneration  in  other 
parts  of  the  body.  Where  a  difference  exists  between  the  rates  with  and 
without  additional  injury  there  is  usually  an  advantage  in  favor  of  the 
part  with  additional  injury.  The  differences  are  however  often  slight 
and  in  some  of  the  cases  come  within  the  limits  of  probable  error.  It 
is  only  when  the  data  as  a  whole  are  taken  that  it  is  possible  to  judge 
of  the  correctness  of  the  general  conclusion  that  within  fairly  wide  limits 
of  additional  injury  there  is  certainly  no  decrease  in  rate  of  regener- 
ation but  rather  a  tendency  toward  an  increase. 

Some  additional  data  on  these  points  have  been  obtained  in  connec- 
tion with  the  present  study  of  the  factors  of  regeneration.  On  the  whole 
they  confirm  the  previous  results.  The  principal  experiment  (Experi- 
ment I)  was  planned  with  a  view  to  further  analysis  of  the  problem, 
especially  the  determination  of  the  effect  of  additional  injury  to  a  like 
organ  as  compared  with  additional  injury  to  an  unlike  organ. 

Experiment  I      Amblystoma  punctatum      Series  4101-4540 

The  young  were  hatched  on  March  29-April  4,  1913,  and  the  oper- 
ations were  made  on  May  4  and  5.  The  measurements  of  the  control 
individuals  at  the  time  of  the  operations  are  given  in  Table  75.  The 
average  total  length  is  31.3  mm.,  the  tail  length  14.4  mm.,  the  average 
length  of  the  fore-legs  3.6  mm.  and  the  average  of  the  hind-legs  1.5  mm. 

The  measurements  of  control  individuals  at  the  end  of  the  experi- 
ment on  May  23  are  given  in  Table  76.  The  total  average  length  is  42.7 
mm.,  the  tail  length  20.0,  the  average  of  the  fore-legs  6.2  and  the  average 
of  the  hind-legs  4.5  mm. 

The  experiment  consisted  in  the  determination  of  the  regenerated 
length  of  the  right  fore-leg  under  three  degrees  of  injury:  when  the 


137]  RATE  OF  REGENERATION— ZELENY  .       137 

right  fore-leg  alone  is  removed,  when  its  mate  is  also  removed  and  finally 
when  its  mate  and  one-half  of  the  tail  are  removed.  In  the  last  two  cases 
the  average  of  the  two  fore-legs  is  taken  as  the  proper  value  for  the 
regeneration 'of  a  fore-leg.  A  large  number  of  individuals,  all  hatched 
from  the  same  lot  of  eggs,  were  used  and  a  selection  of  larvae  was  made 
so  as  to  make  the  experimental  animals  as  nearly  alike  as  possible  in 
this  respect.  In  each  of  the  five  sets  an  individual  for  each  degree  of 
injury  was  killed  at  two  days  after  the  operation,  and  also  at  four,  six, 
eight,  ten,  twelve,  fourteen,  sixteen  and  nineteen  days.  The  data  are 
given  in  Tables  77  to  88.  The  three  degrees  of  injury  may  be  represented 
by  (1)  R,  (2)  R+L,  (3)  R+L+y2T,  in  which  R=right  fore-leg  removed, 
L=left  fore-leg  removed  and  1/2T=one-half  of  the  tail  removed.  The 
second  involves  the  removal  of  some  additional  material  of  the  same 
kind  as  that  removed  in  the  first.  The  third  as  compared  with  the  first 
involves  the  removal  of  some  of  the  same  kind  of  material  and  some  of 
another  kind.  In  every  case  it  is  the  regeneration  of  the  fore-leg  that  is 
used  as  the  basis  of  comparison. 

The  additional  simultaneous  injury  and  regeneration  does  not  de- 
crease the  regeneration  of  the  individual  fore-leg.  At  two  days  the 
average  regenerated  lengths  of  a  fore-leg  are  respectively  0.13,  0.16  and 
0.15  mm.  for  the  three  degrees  of  additional  injury;  at  four  days  the 
corresponding  values  are  0.22,  0.36  and  0.29 ;  at  six  days  0.42,  0.53  and 
0.55;  at  eight  days  0.66,  0.83  and  0.73;  at  ten  days  0.91,  1.34  and  1.24; 
at  twelve  days  1.48,  1.60  and  1.61 ;  at  fourteen  days  1.98,  2.19  and  2.29 ; 
at  sixteen  days  3.02,  3.01  and  3.08 ;  at  nineteen  days  3.84,  3.64  and  3.90. 
At  only  two  of  the  nine  periods  is  the  regeneration  of  the  fore-leg  without 
additional  injury  as  rapid  as  that  of  a  fore-leg  with  additional  injury 
and  at  these  two  times  it  is  less  rapid  than  one  of  the  two  other  groups. 
In  seven  of  the  nine  cases  the  regeneration  of  the  fore-leg  without 
additional  injury  is  less  than  either  of  the  two  with  such  injury. 

Among  the  forty  individual  comparisons  in  which  all  three  degrees 
are  present  the  degree  with  no  additional  injury  has  6%  firsts,  the  degree 
with  an  additional  fore-leg  15%  firsts  and  the  degree  with  an  additional 
fore-leg  plus  one-half  of  the  tail  has  17%  firsts.  Among  the  nine  time 
groups  the  degree  with  no  additional  injury  has  IV3  firsts  and  each  of 
the  additional  injury  combinations  has  3%  firsts. 

Taking  up  the  lowest  positions  in  the  three  degrees  in  the  same  way, 
among  the  forty  individual  comparisons  the  degree  with  no  additional 
injury  gives  the  lowest  regeneration  in  21i/3  cases  while  the  additional 
injury  combinations  each  have  only  9%  lowest  regenerations.  Among 
the  nine  time  groups  the  degree  with  no  additional  injury  has  the  lowest 
value  6  times,  the  one  with  an  additional  removal  of  the  other  fore-leg 


138 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[138 


2y2  times  while  the  one  with  the  highest  degree  of  injury  gives  the  lowest 
regeneration  for  the  fore-leg  only  y2  times. 

These  comparisons  show  very  clearly  that  the  regeneration  of  a  fore- 
leg is  not  as  rapid  when  the  individual  is  regenerating  no  other  part  at 
the  same  time  as  it  is  when  the  other  fore-leg  is  being  regenerated  at 
the  same  time.  The  additional  removal  of  one-half  of  the  tail  does  not 
seem  to  accelerate  the  regeneration  any  further  because  there  is  no  essen- 
tial difference  between  the  effect  of  an  additional  injury  of  a  fore-leg  and 
an  additional  injury  of  a  fore-leg  plus  one-half  of  the  tail.  It  may  be 
that  the  effect  of  additional  removal  is  confined  to  removal  of  a  similar 
part,  the  tail  removal  in  this  case  involving  a  different  kind  of  organ. 
Or  it  may  be  that  the  accelerating  effect  is  found  only  within  certain 
degrees  of  injury  the  limit  being  exceeding  by  the  highest  of  the 
three  degrees. 


TABLE  75 

Amblystoma  punctatum     Series  4101-4540 
Experiment  I     Controls  at  beginning  of  experiment 


Date 

Cata- 
log 
number 

Total 

length 

mm. 

Tail 

length 

mm. 

Fore  legs 

Hind  legs 

Right 

Left 

Av'age. 

Right 

Left 

A.v'age. 

5/4/13 

4110 

3  o.O 

16.4 

4.0 

4.0 

4.0 

3.0 

3.1 

3.05 

5/4/13 

4210 

31.8 

14.8 

3.6 

3.8 

3.7 

1.4 

1.5 

1.45 

5/4/13 

T4310 

28.1 

11.9 

3.3 

3.3 

3.3 

1.0 

0.9 

0.95  I 

5/4/13 

[4320 

33.8 

15.3 

3.3 
3.6 

3.1 

3.2 

1.1 

1.0 

1.05  J 

5/5/13 

4410 

30.2 

13.8 

3.6 

3.6 

1.0 

1.0 

1.0 

5/5/13 

4510 

28.7 

14.0 

3.9 

3.8 

3.85 

1.4 

1.2 

1.3 

Average 

31.3 

14.4 

3.6 

1.5 

139] 


RATE  OF  REGENERATION— ZELENY 


139 


TABLE  76 
Amblystoma  punctatum      Series  4101-4540 
Experiment  I     Controls  at  end  of  experiment 


Date 

Cata- 
log 
number 

Total 

length 

mm. 

Tail 

length 

mm. 

Fore  legs 

Hind  legs 

Right 

Left 

Av'age. 

Right 

Left 

Av'age. 

5/23 

4120 
4130 
4140 

46.7 
44.7 
44.5 

24.3 
21.7 
20.1 

6.1 

6.5 
6.5 

6.1 
6.6 
6.4 

6.1 

6.55 

6.45 

5.0 
5.2 
5.2 

5.0 
5.1 
5.1 

5.0 

5.15 

5.15 

Average 

45.3 

22.0 

6.4 

5.1 

5/23 

4220 
4230 
4240 

43.1 
45.5 
43.7 

20.1 
20.6 
20.4 

6.1 
6.0 
6.0 

6.0 
6.0 
5.5 

6.05 

6.0 

5.75 

4.1 
4.0 
4.0 

4.1 

5.0 
4.4 

4.1 

4.5 
4.2 

Average 

44.1 

20.4 

5.9 

4.3 

5/23 

4330 
4340 

47.2 
41.5 

21.9 
19.5 

7.1 
6.1 

7.2 
6.2 

7.15 
6.15 

5.3 

4.0 

5.2 
4.1 

5.25 
4.05 

Average 

44.3 

20.7 

6.6 

4.6 

5/23 

4420 
4430 
4440 

41.0 
40.5 
40.4 

18.2 
19.4 
18.9 

7.0 
5.6 
6.0 

7.0 
5.6 
6.0 

7.0 
5.6 
6.0 

4.9 
4.0 
4.1 

4.8 
4.1 
4.0 

4.85 
4.05 
4.05 

Average 

40.6 

18.8 

6.2 

4.3 

5/23 

4520 
4530 
4540 

36.5 
40.9 
40.6 

16.0 
18.5 
19.1 

5.6 

6.7 
5.0 

5.6 
6.8 
5.0 

5.6 

6.75 

5.0 

4.0 
4.9 

4.0 

4.0 

4.8 
4.0 

4.0 

4.85 

4.0 

Average 

39.3 

17.9 

5.8 

4.3 

Grand 

average 

42.7 

20.0 

6.2 

4.5 

140 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[140 


TABLE  77 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Two  days 


Degree  of  injury 

Both 

Catalog 

One 

Both 

fore-legs 

number 

fore-leg 

fore-legs 

4-  one-half 
tail 

4101-11-21 

0.10 

0.22 

0.22 

4201-11-21 

0.10 

0.15* 

0.11 

4301-11-21 

0.10 

0.15 

0.17* 

4401-11-21 

0.20 

0.17 

0.20 

4501-11-21 

0.15* 

0.10 

0.07 

Average 

0.13 

0.16* 

0.15 

TABLE  78 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injurj 

Four  days 


Degree  of  injury 

Both 

Catalog 

One 

Both 

fore-legs 

number 

fore-leg 

fore-legs 

+  one-half 
tail 

4102-12-22 

0.25 

0.25 

0.52 

4202-12-22 

— 

0.52 

0.22 

4302-12-22 

0.15 

0.37* 

0.22 

4402-12-22 

0.40* 

0.30 

0.27 

4502-12-22 

0.10 

— 

0.20 

Average 

0.22 

0.36* 

0.29 

141] 


RATE  OF  REGENERATION— ZELENY 


141 


TABLE  79 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Six  days 


Degree  of  injury 

Both 

Catalog 

One 

Both 

fore-legs 

number 

fore-leg 

fore-legs 

+  one-half 
tail 

4103-13-23 

0.40 

0.20 

0.92* 

4203-13-23 

0.50 

0.87* 

0.52 

4303-13-23 

0.45 

0.65* 

0.42 

4403-13-23 

0.45 

0.60* 

0.47 

4503-13-33 

0.30 

0.35 

0.42* 

Average 

0.42 

0.53 

0.55* 

TABLE  80 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury. 

Eight   days 


Degree  of  injury 

Both 

Catalog 

One 

Both 

fore-legs 

number 

fore-leg 

fore-legs 

■f  one-half 

tail 

4104-14-24 

0.50 

0.75 

0.97* 

4204-14-24 

0.80 

0.80 

0.80 

4304-14-24 

0.85 

0.87* 

0.62 

4404-14-24 

0.43 

0.95* 

0.75 

4504-14-24 

0.70 

0.80* 

0.52 

Average 

0.66 

0.83* 

0.89* 

142 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[142 


TABLE  81 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Ten    days 


Degree  of  injury 

Both 

Catalog 

One 

Both 

fore-legs 

number 

fore-leg 

fore-legs 

-f  one-half 

tail 

4105-15-25 

0.25 

1.82* 

1.60 

4205-15-25 

0.95 

1.10* 

1.07 

4305-15-25 

1.05 

1.22 

1.32* 

4405-15-25 

1.20 

1.37* 

1.07 

4505-15-25 

1.10 

1.20* 

1.12 

Average 

0.91 

1.34* 

1.24 

TABLE  82 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Twelve  days 


Degree  of  injury 

Both 

Catalog 

One 

Both 

fore-legs 

number 

fore-leg 

fore-legs 

+  one-half 
tail 

4106-16-26 

1.45 

1.50 

1.77* 

4206-16-26 

1.35 

1.47* 

1.44 

4306-16-26 

1.80* 

1.60 

1.65 

4406-16-26 

1.00 

1.70* 

1.50 

4506-16-26 

1.80* 

1.72 

1.67 

Average 

1.48 

1.60 

1.61* 

143] 


RATE  OF  REGENERATION— ZELENY 


143 


TABLE  83 

Amblystoma  punctatum      Series  4101-4540 
Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Fourteen  days 


Degree  of  injury 

Both 

Catalog 

One 

Both 

fore-legs 

number 

fore-leg 

fore-legs 

+  one-half 
tail 

4107-17-27 

2.60 



2.25 

4207-17-27 

1.70 

1.97 

2.22* 

4307-17-27 

1.45 

1.87 

1.95* 

4407-17-27 

2.25 

2.72 

2.90* 

4507-17-27 

1.90 



2.12 

Average 

1.98 

2.19 

2.29* 

TABLE  84 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Sixteen  days 


Degree  of  injury 

Catalog 
number 

One 
fore-leg 

Both 
fore-legs 

Both 

fore-legs 

-f  one-half 

tail 

4108-18-28 
4208-18-28 
4308-18-28 
4408-18-28 
4508-18-28 

2.60 
2.40 
2.80 
3.60 
3.70 

2.60 

2.62* 

2.67 

3.57 

3.57 

2.70* 

2.22 

2.85* 

3.65* 

3.97* 

Average 

3.02 

3.01 

3.08* 

144 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[144 


TABLE  85 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Nineteen  days 


Degree  of  injury 

Catalog 
number 

One 
fore-leg 

Both 
fore-legs 

Both 

fore-legs 

+  one-half 

tail 

4109-19-29 
4209-19-29 
4309-19-29 
4409-19-29 

4.00* 
3.65 
3.60 
4.10* 

3.72 
4.05 
2.85 
3.95 

3.95 
4.25* 
3.60 
3.80 

Average 

3.84 

3.64 

3.90* 

TABLE  86 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Summary      Two  to  nineteen  days 


1 

Degree  of  injury 

Days 

One 
fore-leg 

Both 
fore-legs 

Both 

fore-legs 

+  one-half 

tail 

2 

0.13 

0.16* 

0.15 

4 

0.22 

0.36* 

0.29 

6 

0.42 

0.53 

0.55* 

8 

0.66 

0.83* 

0.73 

10 

0.91 

1.34* 

1.24 

12 

1.48 

1.60 

1.61* 

14 

1.98 

2.19 

2.29* 

16 

3.02 

3.01 

3.08* 

19 

3.84 

3.64 

3.90* 

Groups  first 
Groups   last 

0 

7 

4 
2 

5 
0 

145] 


RATE  OF  REGENERATION— ZELENY 


145 


TABLE  87 
Amblystoma  punctatum      Series  4101-4540 
Length  of  regenerated  fore-leg  for  different  degrees  of  injury 
Tabulation  of  firsts  for  individual  comparisons 


Injury 

Days 

One 
fore-leg 

Both 
fore-legs 

Both 

fore-legs 

+  one-half 

tail 

2 

1% 

1% 

2* 

4 

1 

1 

1 

6 

0 

3* 

2 

8 

y3 

3H* 

1* 

10 

0 

4* 

1 

12 

2 

2 

1 

14 

0 

0 

3* 

16 

0 

1 

4* 

19 

2 

0 

2 

Total  firsts 

6Ve 

15% 

17J* 

Groups  first 

w 

3% 

3% 

146 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[146 


TABLE  88 
Amblystoma  punctatum     Series  4101-4540 
Length  of  regenerated  fore-leg  for  different  degrees  of  injury 
Tabulation  of  lowest  values  for  individual  comparisons 


Injury 

Days 

One 

fore-leg 

Both 
fore-legs 

Both 

fore-legs 

+  one-half 

tail 

2 

3 

1 

1 

4 

iy2 

1% 

1 

6 

3 

1 

1 

8 

2H 

Vs 

2^ 

10 

4 

0 

1 

12 

3 

1 

1 

14 

3 

0 

0 

'  16 

% 

3% 

1 

19 

i 

2 

1 

Total   lasts 

21^ 

9H 

m 

Groups   last 

6 

2y2 

Vz 

Experiment  II  Amblystoma  punctatum  Series  4101-4540 
This  experiment  deals  with  the  same  series  of  individuals  as  Experi- 
ment I.  The  comparison  in  this  case  however  is  one  between  the  regen- 
eration of  the  removed  half  of  the  tail  when  it  alone  is  removed  and  its 
regeneration  when  there  is  an  additional  removal  of  the  two  fore-legs. 
The  data  are  given  in  Tables  89  to  99.  At  two  days  the  regeneration  of 
the  tail  without  an  additional  injury  is  0.35  mm.  and  with  an  additional 
injury  0.27.  The  corresponding  values  at  4  days  are  0.73  and  0.81,  at 
6  days  1.32  and  1.31,  at  8  days  2.06  and  2.26,  at  ten  days  3.44  and  3.27, 
at  twelve  days  4.36  and  4.20,  at  fourteen  days  4.82  and  4.94,  at  sixteen 
days  5.57  and  6.00  and  at  nineteen  days  5.90  and  6.06.  The  regenerating 
tail  with  no  additional  injury  is  ahead  at  four  times  and  the  one  with 
additional  injury  is  ahead  five  times.    In  thirty  three  individual  com- 


147] 


RATE  OF  REGENERATION— ZELENY 


147 


parisons  the  group  with  no  additional  injury  is  ahead  seventeen  times 
and  the  additional  injury  group  sixteen  times.  Taking  the  individual 
cases  by  time  groups  the  individuals  with  no  additional  injury  are  ahead 
5y2  times  and  those  with  an  additional  injury  3y2  times. 

These  comparisons  show  no  advantage  of  one  combination  over  the 
other.  The  additional  removal  of  the  fore-legs  does  not  retard  nor  does 
it  accelerate  the  regeneration  of  the  tail.  This  result  strengthens  the 
view  that  the  acceleration  in  Experiment  I  is  probably  due  to  the  addi- 
tional removal  of  material  similar  to  that  whose  rate  is  being  studied. 

TABLE   89 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Two  days 


Degree  of  injury 


Catalog 
number 


4131-21 
4231-21 
4331-21 
4431-21 
4531-21 

Average 


One-half 

tail 

+  fore-legs 


0.15 
0.35 
0.25 
0.30 
0.30< 


0.27 


TABLE  90 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Four  days 


Catalog 
number 


4132-22 
4232-22 
4332-22 
4432-22 
4532-22 

Average 


Degree  of  injury 


One-half 

tail 

4-  fore-legs 

1.00* 

0.90 

0.60* 

0.95 

0.60 

0.81* 


148 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[148 


TABLE  91 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Six  days 


Degree 

3f  injury 

Catalog 

One-half 

One-half 

number 

tail 

tail 
+  fore-legs 

4133-23 

1.60 



4233-23 

0.90 

1.00* 

4333-23 

1.70* 

1.65 

4433-23 

1.10 

1.50* 

4533-23 



1.10 

Average 

1.32* 

1.31 

TABLE  92 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Eight   days 


Degree  of  injury 

Catalog 
number 

One-half 
tail 

One-half 

tail 

+  fore-legs 

4134-24 
4234-24 
4334-24 
4434-24 
4534-24 

2.40 

1.80 

1.80 

2.70* 

1.60 

2.60* 
1.90* 
2.26* 
2.30 

Average 

2.06 

2.26* 

149] 


RATE   OF  REGENERATION— ZELENY 


149 


TABLE  93 

Amblystoma  punctatum       Series  4101-4540 
Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Ten  days 


Degree 

of  injury 

Catalog 

One-half 

One-half 

number 

tail 

tail 
+  fore-legs 

4135-25 

3.65* 

3.20 

4235-25 



2.55 

4335-25 

3.20 

1.46 

4435-25 

3.65* 

3.20 

4535-25 

3.25 

4.15* 

Average 

3.44* 

3.27 

TABLE  94 

Amblystoma  punctatum      Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Twelve  days 


Catalog 
number 


4136-26 
4236-26 
4336-26 
4436-26 
4536-26 

Average 


injury 


One-half 

tail 

-f  fore-legs 

4.20* 

3.55 

3.50 

4.50 

5.25* 

4.20 


ISO 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[ISO 


TABLE  95 

Amblystoma  punctatum      Series  4101-4540 
Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Fourteen  days 


Catalog 
number 


4137-27 
4237-27 
4337-27 
4437-27 
4537-27 

Average 


Degree  of  injury 


One-half 

tail 

+  fore-legs 

6.00* 

4.70 

4.95 

4.00 

5.05* 


4.94* 


TABLE  96 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Sixteen  days 


Catalog 
number 


4138-28 
4238-28 
4338-28 
4438-28 
4538-28 

Average 


Degree  of  injury 

One-half 

tail 

-f-  fore-legs 

5.50 

6.40* 

6.10 

6.00* 


151] 


RATE  OF  REGENERATION— ZELENY 


151 


TABLE  97 

Amblystoma  punctatum       Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Nineteen  days 


Degree  of  injury 


TABLE  98 

Amblystoma  punctatum     Series  4101-4540 

Length  of  regenerated  tail  in  millimeters  for  different  degrees  of  injury 

Summary      Two  to  nineteen  days 


Degree  of  injury 

Days 

One-half 
tail 

One-half 

tail 
+  fore-legs 

2 

0-35* 

0.27 

4 

0.73 

0.81* 

6 

1.32* 

1.31 

8 

2.06 

2.26* 

10 

3.44* 

3.27 

12 

4.36* 

4.20 

14 

4.82 

4.94* 

16 

5.57 

6.00* 

19 

5.90 

6.06* 

Groups    first 

4 

5 

152 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[152 


TABLE  99 

Amblystoma  punctatum     Series  4101-4540 

Length  of  regenerated  tail  for  different  degrees  of  injury 

Tabulation    of   firsts    for   individual   comparisons 


Injury 

Days 

One-half 

One-half 

tail 

tail 

+  fore-legs 

2 

2%* 

1% 

4 

2% 

2% 

6 

1 

2* 

8 

1 

3* 

10 

2* 

1 

12 

3* 

2 

14 

3* 

2 

16 

1 

1 

19 

1 

1 

Total  firsts 

17 

16 

Groups  first 

5«/2 

3J/2 

Experiment  III      Amblystoma  punctatum      Series  4005-4008 


Experiments  III,  IV,  V  and  VI  comprise  merely  a  few  individual 
comparisons  obtained  from  experiments  devised  principally  for  the 
study  of  other  factors.  They  are  included  here  under  the  rule  that  no 
valid  data  on  the  matter  at  hand  are  to  be  excluded. 

In  Experiment  III  the  regeneration  of  the  hind-leg  is  compared 
under  the  four  conditions  of  (1)  no  additional  injury,  (2)  removal  of 
the  other  hind-leg,  (3)  removal  of  the  other  hind-leg  and  one  fore-leg 
and  (4)  removal  of  the  other  hind-leg  and  both  fore-legs.  The  data 
are  given  in  Table  100. 

Three  sets  of  comparisons  were  made  at  twelve  days  after  the  oper- 
ations, each  with  a  single  individual  for  each  degree  of  injury.  The 
regenerating  hind-leg  with  no  additional  injury  is  distinctly  behind  the 
cases  with  additional  injury.  The  greatest  regenerated  length  comes  in 
one  case  with  an  additional  injury  of  one  hind-leg  plus  one  fore-leg  and 
in  two  cases  with  one  hind-leg  plus  two  fore-legs.    The  averages  begin- 


153] 


RATE  OF  REGENERATION— ZELENY 


153 


ning  with  the  lowest  degree  of  injury  are  respectively  1.50,  1.73,  1.86 
and  1.88  mm. 

The  additional  removals  are  in  every  ease  removals  of  leg  material 
and  the  result  agrees  with  that  of  experiment  I  in  giving  an  increased 
rate  of  regeneration  of  a  part  when  similar  organs  are  removed  at  the 
same  time. 

TABLE  100 
Amblystoma  punctatum      Series  4005-4008 
Length  of  regenerated  hind  leg  in  millimeters  for  different  degrees  of  injury- 
Twelve   days 


Catalog 
number 


4005 
4006 
4008 


Average 


One 
hind-leg 


1.35 
1.65 
1.50 


1.50 


Degree  of  injury 


Both 
hind-legs 


1.90 
1.80 
1.50 


1.73 


Both  hind- 

legs+one 

fore-leg 


1.95" 
1.82 
1.80 


1.86* 


Both  hind- 

legs+both 

fore-legs 


1.75 

1.92" 

1.85" 


1.84 


TABLE  101 

Amblystoma  punctatum      Series  4005-4008 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Twelve   days 


Degree  of  injury 

Catalog 

number 

One 

Both 

fore-leg 

fore-legs 

+  both 

+  both 

hind-legs 

hind-legs 

4005 

3.0* 

2.8 

4006 

3.1* 

3.0 

4008 

3.0 

3.15* 

Average 

3.07* 

2.98 

Experiment  IV      Amblystoma  punctatum      Series  4005-4008 

In  this  experiment  the  regeneration  of  the  right  fore-leg  is  compared 
under  conditions  of  differing  degrees  of  additional  injury.  In  one  com- 
bination there  is  an  additional  removal  of  the  two  hind  legs  and  in  the 


154 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[154 


other  of  both  hind-legs  plus  the  remaining  fore-leg.  The  data  are  given 
in  Table  101.  In  two  of  the  three  cases  the  smaller  additional  degree  of 
injury  shows  the  greater  regeneration  of  the  fore-leg.  The  average  is 
3.07  mm.  for  the  lesser  degree  and  2.98  for  the  greater  degree,  an 
advantage  in  favor  of  the  lesser  degree. 

It  should  be  noted  that  this  is  not  strictly  comparable  with  the 
main  issue  of  Experiments  I,  II  and  III.  Aside  from  the  small  number 
of  cases  it  is  a  comparison  between  two  degrees  of  injury  each  of  which 
is  of  considerable  extent.  It  may  be  that  the  removal  of  three  of  the 
four  legs  is  near  the  degree  of  injury  yielding  the  maximum  rate  for  each 
removed  leg. 

Experiment  V      Ambltstoma  punctatum      Series  4010-4025 

A  comparison  is  made  between  the  regeneration  of  a  half  of  the  tail 
when  it  alone  is  removed  and  when  both  fore-legs  are  removed  at  the 
same  time.  Four  individual  comparisons  are  made  at  fourteen  days. 
The  data  are  given  in  Table  102.  The  regenerated  lengths  and  specific 
lengths  regenerated  are  ahead  in  two  of  the  four  cases  for  each  of  the 
degrees  of  injury.  The  average  regenerated  length  with  no  additional 
injury  is  5.1  mm.  and  with  additional  injury  5.0  mm.  The  specific 
regenerated  length  is  0.65  with  no  additional  injury  and  0.68  with  addi- 


TABLE  102 

Amblystoma  punctatum       Series  4010-4025 

Regeneration  of  tail  for  different  degrees  of  injury 

Fourteen  days 


Degree 

of  injury 

One-half  tail 

One-half  tail  +  both  fore-legs 

Catalog 
number 

Length 
removed 

Length 
regener- 
ated 

Specific 
amt.  re- 
generated 

Length 
removed 

Length 
regener- 
ated 

Specific 
amt.  re- 
generated 

4014-13 

7.7 

4.9 

0.64 

7.0 

5.2* 

0.74* 

4018-17 

8.8 

5.2* 

0.59* 

8.0 

4.3 

0.54 

4022-21 

8.0 

5.3* 

0.66* 

8.0 

5.1 

0.64 

4025-24 

7.0 

4.9 

0.70 

6.6 

5.3* 

0.80* 

Average 

5.1 

0.65 

5.0 

0.68 

155] 


RATE  OF  REGENERATION— ZELENY 


155 


tional  injury.  The  data  show  essential  equality  between  the  rates  of 
regeneration  under  the  two  conditions  of  the  experiment.  This  agrees 
with  the  data  in  Experiments  I  and  II  which  show  no  increase  or  decrease 
in  rate  of  regeneration  when  unlike  material  is  removed  simultaneously 
with  the  removal  of  the  organ  whose  rate  is  being  studied. 

Experiment  VI      Amblystoma  punctatum      Series  4010-4025 

Three  individual  comparisons  were  made  at  fourteen  days  of  the 
right  fore-leg,  when  it  alone  is  removed,  when  the  other  fore-leg  is  also 
removed  and  when  the  other  fore-leg  plus  one  half  of  the  tail  is  removed. 
The  data  are  given  in  Table  103.  In  two  of  the  three  cases  the  individuals 

TABLE  103 

Amblystoma  punctatum      Series  4010-4025 

Length  of  regenerated  fore-leg  in  millimeters  for  different  degrees  of  injury 

Fourteen  days 


Catalog 
number 


4011, 12, 13 
4015, 16, 17 
4019,  20,  21 
4023,  — ,  24 


Average 


Degree  of  injury 


One 
fore-leg 


2.00* 
2.00* 
1.95 
2.00 


1.99* 


Both 
fore-legs 


1.77 
1.60 
1.82 


1.73 


Both 

fore-legs 

-f-  one-half 

tail 


1.65 
1.80 
2.22* 
2.00 


1.92 


with  no  additional  regeneration  are  ahead  of  the  others.  The  greater 
injury  gives  the  greater  rate  in  one  of  the  three.  The  average  regener- 
ated lengths  beginning  with  the  lowest  degree  of  injury  are  respectively 
1.99,  1.73  and  1.92  mm.  The  few  cases  may  be  a  sufficient  explanation 
of  the  lack  of  agreement  with  the  more  extended  series  of  Experiment  I. 

Discussion 

The  experiments  as  a  whole  show  that  a  part  regenerates  slightly 
more  rapidly  when  additional  material  of  the  same  kind  is  removed  than 
when  the  part  alone  is  removed.  Simultaneous  removal  of  tail  material 
does  not  accelerate  the  regeneration  of  a  leg  nor  does  simultaneous  re- 
moval of  a  leg  accelerate  the  regeneration  of  the  tail.  The  rate  in  these 
cases  however  is  not  decreased  by  the  additional  injury.     The  state- 


156  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [156 

ment  may  therefore  be  made  that  within  limits  the  regeneration  of  a  part 
is  not  retarded  by  simultaneous  removal  and  regeneration  of  material  in 
other  parts  of  the  body.  When  this  additional  material  is  of  the  same 
kind  as  that  whose  rate  is  being  studied  there  may  even  be  an  acceler- 
ation of  regeneration. 

In  comparison  with  such  a  factor  as  level  of  the  cut  this  difference 
in  rate  is  slight  and  no  such  quantitative  relation  as  in  that  case  can  be 
made  out.  It  must  however  be  considered  that  the  principal  object  of  the 
original  experiments  was  to  show  that  additional  injury  within  the  given 
limits  tends  to  increase  rather  than  decrease  the  rate  of  regeneration. 
This  has  been  proved  for  these  experiments.  The  evidence  in  favor  of 
a  definite  increase  in  rate  with  any  certain  increase  in  degree  of  injury 
is  not  so  conclusive.  It  is  obvious  that  in  many  series  of  experiments 
factors  whose  influence  is  greater  than  that  of  the  factor  under  discus- 
sion may  obscure  the  result. 

Emphasis  should  again  be  placed  on  the  fact  that  all  data  obtained 
by  the  writer  are  included.  That  some  of  the  series,  especially  those  with 
a  few  individuals,  diverge  from  the  general  result  is  to  be  expected  by 
anyone  in  similar  work  who  has  attempted  to  eliminate  entirely  all  of  the 
factors  except  the  one  under  observation  at  a  particular  time. 

Summaky 

1.  A  comparison  was  made  of  the  rate  of  regeneration  of  a  leg  or 
of  the  tail  of  an  Amblystoma  larva  when  the  part  alone  is  removed 
with  its  rate  when  similar  or  dissimilar  parts  of  the  individual  are 
removed  at  the  same  time.  The  data  are  derived  from  two  principal 
Experiments,  I  and  II,  and  from  a  few  scattered  observations  listed  as 
Experiments  III  to  VI. 

2.  In  Experiment  I  a  comparison  was  made  of  the  rate  of  regener- 
ation of  the  right  fore-leg  when  it  alone  is  removed  with  its  rate  when 
the  other  fore-leg  is  removed  at  the  same  time  and  when  the  other  fore- 
leg and  one  half  of  the  tail  are  removed.  The  result  obtained  from  forty 
individual  comparisons  made  at  different  times  shows  that  the  rate  of 
regeneration  of  the  right  fore-leg  in  each  of  the  series  with  additional 
injury  is  greater  than  in  the  series  without  additional  injury. 

3.  The  rate  of  regeneration  of  a  right  fore-leg  when  its  mate  plus 
one-half  of  the  tail  is  removed  is  not  essentially  different  from  the  rate 
when  its  mate  alone  is  removed.  The  addition  of  the  injury  to  a  dissimilar 
organ,  the  tail,  does  not  alter  the  rate  of  regeneration  of  the  fore-legs. 

4.  In  Experiment  II  it  is  shown  that  there  is  no  significant  differ- 
ence between  the  rate  of  regeneration  of  a  tail  one-half  of  which  has  been 


157]  RATE  OF  REGENERATION— ZELENY  157 

removed  without  additional  injury  to  the  individual  and  the  rate  after 
the  same  injury  plus  a  removal  of  both  fore-legs. 

5.  The  data  of  Experiments  III  to  VI  show  some  departures  from 
the  general  rule  probably  because  they  deal  with  few  individuals.  On 
the  whole  however  they  bear  out  the  results  obtained  from  the  principal 
experiments. 


158  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [158 


PART  VI 

THE  COMPLETENESS  OF  REGENERATION 

One  of  the  striking  facts  in  connection  with  amphibian  regeneration 
as  made  out  in  the  present  studies  is  the  lack  of  completeness  of  the 
process.  When  a  part  of  the  tail  is  removed  the  lost  part  is  never  com- 
pletely restored.  Data  on  this  problem  are  to  be  found  in  a  number  of 
sets  of  experiments  one  of  which  (Experiment  V)  was  devised  especially 
for  the  present  purpose. 

Experiment  I      Rana  clamitans      Series  3557-3624 

One-half  of  the  tail  was  removed  in  the  individuals  of  three  groups, 
A,  B  and  C.  After  35  to  39  days,  which  was  sufficiently  long  so  that 
regeneration  had  stopped,  another  removal  was  made  and  so  on  until  each 
individual  had  undergone  five  regenerations.  The  data  are  given  in 
Table  104.  The  average  removed  length  as  estimated  from  the  measure- 
ment of  a  few  individuals  was  17.0  mm.  The  average  length  of  the  com- 
pleted first  regeneration  is  8.6  mm.  or  51  per  cent  of  the  removed  length, 
of  the  second  regeneration  8.0  mm.  or  53  per  cent,  of  the  third  7.5  mm. 
or  51  per  cent,  of  the  fourth  5.5  mm.  or  42  per  cent  and  of  the  fifth 
6.4  mm.  of  45  per  cent.  On  the  average  about  one-half  of  the  removed 
length  is  replaced  when  one-half  of  the  tail  length  is  removed. 

Experiment  II      Rana  clamitans      Series  3628-3675 

One-half  of  the  tail  length  was  removed  in  the  individuals  of  this 
experiment  and  regeneration  was  allowed  to  proceed  for  twenty  days, 
a  sufficient  time  for  bringing  it  to  a  stop.  The  data  are  given  in  Table 
105.  The  average  original  tail  .length  was  21.8  mm.,  of  the  removed 
length  10.6  mm.  and  of  the  regenerated  length  5.4  mm.  The  completed 
regenerated  length  is  thus  51  per  cent  of  the  removed  length. 

Experiment  III      Rana  clamitans      First  regenerations 
Series  3676-3765 

The  data  are  given  in  Table  106.  The  tails  were  removed  at  different 
levels  approximating  6,  10,  17,  30,  48  and  62  per  cent  of  the  tail  lengths. 
Regeneration  was  completed  at  these  levels  at  12^2,  12%,  12V2>  18,  18 


159] 


RATE  OF  REGENERATION— ZELENY 


159 


and  56  days  respectively.  The  regenerated  lengths  at  these  times  of 
completion  are  respectively  61,  46,  39,  33,  42  and  41  per  cent  of  the 
removed  lengths.  It  will  be  noted  that  the  two  shortest  removals  give 
the  highest  per  cents  and  the  two  medium  ones  the  lowest  per  cents. 
This  difference  is  discussed  in  Part  III  on  the  effect  of  level  of  the  cut. 


Experiment  IV      Kana  clamitans      Second  regenerations 
Series  3676-3765 

The  data  are  given  in  Table  107.  The  tail  was  removed  at  different 
levels  approximating  6,  10,  18,  31,  49  and  67  per  cent  of  the  removed 
lengths.    Regeneration  was  completed  for  these  levels  at  10,  10,  12%, 

TABLE   104 

Rana  clamitans       Series  3557-3624       Completeness  of  regeneration 
Successive   regenerations   in   single   individuals       One-half   of  tail   removed  ■= 
17  mm.  on  the  average      First  operation  Oct.  23,  1911       Second  operation 
Groups  A  and  B  Nov.  18      Group  C  Nov.  28 


First 

Second 

Third 

Fourth 

Fifth 

regener- 

regener- 

regener- 

regener- 

regener- 

Catalog 

ation 

ation 

ation 

ation 

ation 

number 

Nov.  28 

Jan.  3 

Feb.  9 

Mar.  16 

April  24 

3564 

9.5 

8.5 

— 

— 

3565 

9.8 

11.4 

7.3 

8.2 

3566 

10.0 

9.3 

8.1 

6.3 

Group 

3567 

11.9 

9.5 

8.0 

11.9 

A 

3568 

8.4 

9.9 

11.0 

8.5 

3569 

10.0 

8.7 

8.0 

8.1 

3570 

8.7 

8.1 

— 

— 

Average 

9.8 

9.3 

8.5 

8.6 

3578 

8.3 

9.0 

5.8 

8.2 

3579 

8.2 

8.1 

11.3 

7.0 

3580 

11.9 

7.3 

6.9 

8.1 

Group 

3581 

9.7 

8.0 

7.6 

11.6 

B 

3582 

8.3 

12.8 

7.4 

5.4 

3583 

8.8 

7.4 

5.0 

6.8 

3584 

8.8 

9.5 

6.4 

— 

Average 

9.1 

8.9 

7.2 

7.8 

160 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[160 


TABLE  104  (Continued) 


First 

Second 

Third 

Fourth 

Fifth 

regener- 

regener- 

regener- 

regener- 

regener- 

Catalog 

ation 

ation 

ation 

ation 

ation 

number 

Nov.  28 

Jan.  3 

Feb.  9 

Mar.  16 

April  24 

3586 

8.1 

— 

— 

— 

— 

3588 

6.1 

7.5 

7.3 

5.7 

7.2 

3590 

8.5 

6.6 

7.5 

5.1 

6.5 

3592 

7.1 

8.0 

5.7 

4.9 

6.5 

3594 

8.6 

7.8 

2.0 

5.0 

6.1 

3596 

9.0 

8.6 

9.4 

6.7 

6.8 

3598 

10.7 

9.7 

9.3 

6.1 

6.2 

3600 

8.2 

8.0 

6.9 

5.8 

5.9 

3602 

9.9 

7.7 

6.8 

4.4. 

4.7 

Group 

3604 

9.6 

7.6 

6.6 

4.9 

5.7 

C 

3606 

7.4 

7.8 

8.0 

5.0 

5.9 

3608 

9.0 

8.0 

9.0 

5.5 

6.9 

3610 

8.5 

8.9 

8.3 

5.4 

7.1 

3612 

7.4 

7.0 

7.1 

4.8 

5.5 

3614 

8.3 

6.6 

6.2 

4.5 

5.2 

3616 

8.0 

8.3 

7.9 

6.1 

7.9 

3618 

9.7 

9.5 

9.7 

7.3 

8.0 

3619 

— 

8.0 

7.5 

6.6 

6.1 

3622 

10.2 

8.5 

— 

— 

— 

3624 

9.3 

7.5 

— 

Average 

8.6 

8.0 

7.5 

5.5 

6.4 

Percent 

Df  removed 

■ 

length    r 

egen.      Av. 

51 

53 

51 

42 

45 

1214,  56  and  56  days  respectively.  The  regenerated  lengths  at  these  times 
of  completion  are  respectively  67,  46,  33,  31,  40  and  39  per  cent  of  the 
removed  lengths.  As  in  the  case  of  the  first  regenerations  the  two  shortest 
removals  give  the  highest  per  cent  of  regeneration  and  the  two  medium 
removals  the  lowest  per  cent. 

Experiment  V      Amblystoma  punctatum      Series  6212-6281 

The  experiments  on  tadpoles  of  Rana  clamitans  having  shown  that 
only  a  half  or  less  of  the  removed  length  on  the  average  is  completed  dur- 
ing regeneration  it  became  a  matter  of  interest  to  see  if  this  might  not 
have  been  due  to  the  age  of  the  tadpoles,  which  were  obtained  in  the  fall. 
Accordingly  a  series  of  Amblystoma  larvae  was  operated  upon  within  a 


161] 


RATE  OF  REGENERATION— ZELENY 


161 


few  days  after  they  had  left  the  egg  envelopes  and  was  kept  until  the 
salamanders  were  well  advanced  in  their  metamorphosis.  Since  in  young 
salamander  larvae  the  border  line  between  old  and  regenerated  tissue  is 
soon  obliterated  it  became  necessary  to  devise  another  method  of  testing 
completeness  of  regeneration  than  the  direct  measurement  of  the  regen- 


TABLE  105 
Rana  clamitans      Series  3628-3675 


Regenerated 

Tail 

Removed 

length 

length 

length 

Twenty 
days 

24.1 

13.1 

5.9 

24.6 

13.2 

5.2 

22.1 

11.0 

4.9 

23.2 

11.1 

5.5 

23.1 

11.7 

5.9 

25.0 

12.5 

5.8 

20.4 

9.9 

5.6 

20.8 

10.0 

5.2 

29.2 

15.5 

5.9 

23.8 

10.5 

5.6 

23.3 

10.9 

5.6 

25.6 

10.9 

5.9 

20.8 

10.1 

4.7 

19.2 

9.8 

4.6 

21.1 

11.5 

5.5 

22.0 

11.8 

6.1 

17.0 

8.2 

5.6 

19.0 

9.7 

5.5 

22.4 

9.8 

4.3 

19.8 

10.1 

5.2 

20.8 

8.4 

5.1 

21.8 

9.1 

5.0 

15.4 

7.3 

6.0 

18.1 

9.0 

6.0 

21.8 

10.6 

5.4 

Percent 

removed 

49 

Percent    of 

removed 

part  rege 

derated 

51 

162 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[162 


TABLE  106 
Rana   clamitans      Series    3676-3765      First   regenerations 


Average 

Percent 

Tail 

maximum 

Average 

Days  after 

Number 

of  tail 

length 

regeneration 

maximum 

operation 

of 

length 

removed 

in 

regeneration 

when  maxi- 

cases 

removed 

in  mm. 

percent  of 

in  mm. 

mum  is 

Average 

Average 

removed 
length 

reached 
Average 

2 

6 

1.5 

61 

0.9 

12% 

5 

10 

2.6 

46 

1.2 

12% 

3 

17 

4.6 

39 

1.8 

12% 

8 

30 

8.2 

33 

2.7 

18 

5 

48 

13.0 

42 

5.5 

18 

5 

62 

16.7 

41 

6.9 

56 

TABLE  107 
Rana  clamitans     Series  3676-3765     Second  regenerations 


Average 

Percent 

Tail 

maximum 

Average 

Days  after 

Number 

of  tail 

length 

regeneration 

maximum 

operation 

of 

length 

removed 

in 

regeneration 

when  maxi- 

cases 

removed 

in  mm. 

percent  of 

in  mm. 

mum  is 

Average 

Average 

removed 
length 

reached 
Average 

4 

6 

1.5 

67 

1.0 

10 

7 

10 

2.8 

46 

1.3 

10 

5 

18 

4.9 

33 

1.6 

12% 

10 

31 

8.4 

31 

2.6 

12% 

8 

49 

13.1 

40 

5.2 

56 

10 

67 

18.1 

39 

7.1 

56 

163]  RATE  OF  REGENERATION— ZELENY  163 

erated  material.  This  consisted  in  a  comparison  of  the  ratio  between  tail 
length  and  body  length  in  the  operated  individuals  with  that  in  control 
unoperated  individuals.     This  was  done  after  regeneration  had  been 

tail 
going  on  during  the  whole  larval  period.    If  the  }r~T~  period  is  the  same 

in  operated  as  in  unoperated  individuals  it  is  proper  to  suppose  that 
regeneration  has  been  complete.  If  however  the  ratio  is  lower  the 
conclusion  that  regeneration  is  incomplete  is  very  probably  correct 
though  absolute  certainty  can  not  be  assumed  because  of  the  possibility 
of  the  changed  ratio  being  due  to  regulatory  changes  in  other  parts  of  the 
individual. 

The  experiment  consists  of  a  comparison  of  the  relative  degree  of 
completeness  of  regeneration  of  the  tail  in  four  groups,  (1)  with  no 
operation,  (2)  with  one-fourth  of  the  tail  removed,  (3)  with  one-half 
of  the  tail  removed  and  (4)  with  three-fourths  removed.  The  operations 
were  made  as  soon  as  possible  after  the  animals  left  the  egg  envelopes 
and  the  experiment  proceeded  until  all  four  legs  were  well  developed 
and  absorption  of  the  gills  had  begun.  This  allowed  practically  the  entire 
larval  period  for  regeneration.  There  were  seventy  individuals  at  the 
start  but  a  high  mortality  reduced  the  number  very  considerably.  Lim- 
nodrilus  was  used  as  food. 

The  data  are  given  in  Tables  108  to  112.  The  average  ratio  between 
tail  and  body  length  in  control  individuals  at  the  end  of  the  experiment 
is  1.09,  in  individuals  with  one-fourth  of  the  tail  removed  it  is  1.01,  in 
those  with  one-half  removed  0.93  and  with  three-fourths  removed  0.86. 
This  progressive  relative  decrease  in  the  tail  length  as  compared  with  the 
body  length  is  very  probably  due  to  lack  of  completeness  of  regeneration 
even  though  the  whole  larval  period  has  been  allowed  for  such  completion. 

Discussion 

Apart  from  the  starting  stimulus  in  regeneration  the  most  interesting 
problem  is  undoubtedly  that  of  the  stopping  stimulus.  With  the  growth 
once  started  what  are  the  factors  involved  in  checking  it  1  In  general  it 
has  been  assumed  that  regeneration  goes  on  until  the  removed  organ  is 
entirely  replaced  and  that  over-  and  under-regeneration  occur  but  rarely. 
The  present  data  make  it  probable  that  incompleteness  is  more  general 
than  has  been  supposed.  The  factors  at  work  in  bringing  regeneration 
to  a  close  tend  to  overdo  rather  than  underdo  their  function. 

A  further  investigation  of  the  problem  of  completeness  of  regener- 
ation would  be  of  interest. 


164 


ILLINOIS  BIOLOGICAL  MONOGRAPHS 


[164 


T. 


4_9 

,_ 

a 
B 

*3 

o 

^ 

n 

os 

M 

r~. 

O 

o 

00 

U5 

o 

rH 

os 

a 

•S3 

o 

iH 

o 

rH 

rH 

© 

T- 

— 

o 

q 

*n 

i-i 

H 

1-i 

tA 

rH 

— 

rH 

T-i 

rH 

!• 

<o 

3 

K 

8 

O    rH 

OS 

•O    rH 

H  3 

£~ 

eo 

oo 

io 

cc 

— 

l-( 

O 

OS 

eg 

^f 

-a  to 

eo 

^i 

id 

1ft 

-T 

to 

n 

■♦ 

us 

9  i 

ut 

"• 

» 

■-* 

00 

eo 

OS 

■* 

eo 

CO 

bo 

'3  * 

■* 

-r 

co 

t"! 

id 

--;' 

*j 

te 

to 

in' 

rH      fl 

.2 

1 

T" 

•" ■ 

© 

5 

—  .d 

00 

CNJ 

■* 

e-i 

*i 

Tt< 

OS 

CO 

la 

CM 

-S    60 

l> 

t» 

ei 

eo" 

d 

— i 

r~ 

rH 

o 

d 

cq 

N 

CO 

eo 

CO 

eo 

<M 

eo 

eo 

co 

9 

ri 
J 

"3 

>> 

-a 
o 

"E 

H 

m 

1-1 

oo 

oo 

iH 

cnj 

OS 

00 

eo 

■* 

N. 

& 

x 

6 

X 

t-; 

t- 

oo 

r- 

EC 

t^ 

i- 

00 

fs. 

© 

d 

© 

c= 

d 

O 

d 

o 

o 

d 

3 

« 

3 

<W 

K 

O 

-    r. 
CI    OS 

CQ  5 

00 

co 

BO 

CO 

go 

C-3 

CO 
00 

eo 

oo 

CO 

'5b  H 

©  — 

n  t: 

<1 

eo 

© 

© 

t- 

© 

"^1 

■* 

CO 

o 

CXI 

■ 

es    bo 

CO 

id 

co 

co 

CO 

us 

CD 

co 

t> 

d 

■d 

H| 

bO 

a 

© 

•■* 

00 

35 

rH 

t« 

b; 

© 

eo 

M 

CO 

os 

eo 

CO 

2 
> 

3 

Eh     a 

tJ* 

r? 

M 

L~ 

■*« 

re 

■J 

-» 

id 

bO  fis 

V 

5  a 

00 

N 

eo 

CO 

t» 

CO 

t- 

CO 

00 

ra 

rH 

•M 

■M 

DC 

eo 

■* 

>♦ 

CO 

CO 

cn 

ri 

M 

M 

B4 

■M 

•M 

^] 

e<i 

4) 

a)     r 

CO 

CO 

•-5 

^ 

CO 

CO 

CO 

CO 

CO 

> 

o 

d 

< 

165] 


RATE  OF  REGENERATION —ZELENY 


165 


ii 

-•-> 

© 

_ 

>> 

iH 

00 

■* 

CNI 

T- 

•o 

T-l 

O) 

© 

OS 

o 

a 

a 

o 
PQ 

1-i 

© 

T- 1 

o 

o 

© 

«M 

IS 

>> 

CM 

CD 

© 

■*. 

CO 

o 

1— 1 

OS 

o 

PQ 

bo 

id 

CO 

■*< 

■*' 

^t 

t3 

iH 

(3 
0> 

" 

iH 

IH 

1-1 

T~ 

OS 

T3 

H 
oa 

a 

p 

i 

© 

> 
O 

a 

43 

00 

CO 

io 

w 

■O 

43 

•-» 

"3 

bO 

d 

CO 

•* 

CO 

■* 

© 

bO 

H 

a 

tH 

rH 

iH 

7-t 

,~ 

^H 

= 

"3 

0) 

,"H 

O 

.2 

"3 

43 

© 

OS 

US 

t~ 

CO 

*-> 

IS 

O 

on 

CN* 

-.- 

od 

t~ 

00 

M 

3 
© 

CO 

CI 

:i 

CNI 

CM 

S3 
O 

© 

i 

i 

a 

? 

I 

O 

v 

t- 

oc 

t- 

iH 

00 

CM 

CNI 

71 

CO 

CM 

a 

53 

d 

© 

o 

o 

d 

at    i-t 

o  oo 

rH    « 
CO 

■u 

© 

a 

3 

-o 

a 

3  s 

© 

— 

V 

"a 

9 

a 

t- 

1— 

co 
i-i 

o 
c4 

N; 

2  s 

H   © 

X 

© 

© 

© 

K 

i-^ 

«M 

o 

i 

-a 

02 

bO 

IO 

I 

CO 

OS 

o 

CD 

CO 

a 

1-1 

| 

© 

00 

© 

o 

d 

3 
-u 

"So 

0) 

i-i 

* 

O 

£3 
3 

- 

>> 

to 
B 

CM 

CD 

■"* 

la 

o> 

< 

o 

00 

t> 

t~ 

00 

r»I 

A 

PQ 

08 

■u 

a 

o 

a 
© 

43 

n 

*j 

CNI 

© 

os 

1a 

>} 

00 

3 

bo 

CD 

CD 

id 

CO 

CD 

3 

a 

a 

H 

c 
9 

V 

^* 

^ 

3 

_ 

43 

2 

+j 

■* 

CD 

CO 

o 

»■ 

<0 

o 

Eh 

bo 

a 

■«*" 

CO 

CO 

io 

rt 

rH 

iH 

iH 

tH 

M 

o 

Sh 

CJ 

© 

42 

T* 

-*• 

OS 

1ft 

a> 

ra 

"3 

a 

CO 

■** 

"• 

CD 

L. 

CM 

N 

n 

CM 

« 

ej 

a 

CO 

CD 

«C 

CD 

> 

o 

a 

< 

-u 

1 

1 

a 
© 

a 

^- 

>» 

-<*< 

CD 

irt 

b- 

co 

3 

13 
O 

PQ 

o 

y~. 

OS 

00 

OS 

i-i 

d 

d 

d 

d 

© 

Ii 

© 

0-1 

IO 

>. 

43 

o 

-r 

b> 

CM 

co 

O 

iH 

OS 

o 

PQ 

bo 

T(" 

-71 

T< 

CO 

CO 

g 

r-l 

a 
© 

iH 

H 

1-1 

1-1 

'*- 

0 

OS 

iH 

© 

> 

O 

a 

00 

Q 

„H 

43 

-4-> 

IO 

6" 

e 

to 

i»- 

<D 

J3 

its 

3 

bO 

TjJ 

d 

--' 

iH 

cO 

h 

W) 

P 

S 
© 

1-1 

iH 

H 

iH 

'1~ 

^—| 

c 

a 

© 

c 

<M 

•a 

o 

© 

3 

43 

-4-> 

in 

i-j 

i- 

t> 

M 

<M 

53 

O 
ft 

bO 

00 

CO 

ad 

Tl" 

d 

3 

J3 

w 

(3 

_© 

CM 

7i 

<M 

<M 

CM 

cb 

a 

1 

O 

•?     ' 

1 

> 

-* 

o 

c- 

OS 

O 

Ss 

a 

M 

d 

CO 

d 

d 

d 

■o 
d 

r-i  g 

p 

© 

'3 

a  3 

PI 
© 

a 

Pi 

H 

3     CM 

a  h 

'O 

PQ  w 

43 

© 

> 

a 
© 

bo 

a 

© 

00 
CM 

acj 

co' 

IO 
CO 

CO 
CO 

© 

© 
o 

Pi 

•* 

w 

bO 

U5 

— 

1 

o 

PQ 

OS 

to 

t- 

00 

^ 

a 

c 
'3 

OS 

iH 

'3 

t- 

d 

d 

30 

d 

00 

d 

CO 

d 

+j 

c 

OS 

cfl 

o 

'bfl 
© 

1-1 

a 

PQ 

T3 

X3 

p 

p< 

>> 

S 

o 

co 

CO 

SNJ 

fH 

p< 

cS 

a 

CO 

< 

o 

PQ 

bO 
1 
© 

00 

ad 

l> 

oo 

CO 

o 

bO 

c 
© 

CO 

>> 

43 

+■> 

CO 

n 

00 

CM 

cq 

■fi 

a 

bo 

3 

bO 

d 

d 

d 

t> 

d 

.S 
> 

S 

P 
© 

3 

^_ 

43 

a 

S 

CO 

CO 

CD 

■«cn 

h« 

■w 

O 

bO 

© 

iH 

i-( 

iH 

e 

bO 

»- 

V 

2 

© 

42 

OS 

O 

IO 

T»< 

re 

3 

4-> 

a 

CO 

iO 

U9 

CO 

s_ 

CM 

•M 

<N 

CM 

V 

cd 

a 

CO 

te 

CO 

CO 

> 

O 

(3 

< 

166 


ILLINOIS  BIOLOGICAL   MONOGRAPHS 


[166 


iH  00 

r-i  £2 

•<J  eo 

H  CO 


o> 

£ 

5 

o 
d 
a 

1 
O 
«3 

03 

3 

i 


4J 

1 

g 

1 

O 

CQ 

eo 

h- 

t- 

CD 

3 

Oi 

© 

© 

00 

© 

00 

d 

5 

Pi 

X 

CD 

hi 

xi 

IN 

rH 

CO 

CO 

T3    tH 

o 

PQ 

OJD 

a 

Lffl 
tH 

OS 

eo 

CM 

C     OS 

""" 

0 

a 

A 

J3    H| 

'3 

bfl 

r-j 

© 

o 

M 

H 

d 

r-l 

tH 

*" 

a 

5 

a> 

d 

£ 

eo 

iH 

1ft 

CO 

r^ 

o 

H 

bo 

Oi 

CO 

lO 

eo 

a 

a 

cq 

iH 

N 

CM 

*   I' 

> 

r~ 

o 

**• 

c- 

t» 

r^ 

s 

55 

o 

o 

o 

^ 

<D 

3 

a 

£ 

H 

a> 

8 

-a 

j3 

u 

> 

*t 

M 

CO 

a 

bfi 

-«»< 

■«*< 

•*< 

Tf 

X 

CD 

<D 

<x> 

Pi 

o 

MS 

1 

-a 
o 

PQ 

eo 

OS 

© 

en 

a  as 
"3  H 

00 

© 

d 

d 

d 

5  » 

60  H 

1 

<1>    — i 

a. 

>» 

t- 

t- 

o 

CO 

<S 

o 

bo 

t- 

t- 

•00 

r«* 

£j 

n 

S 

60 

a 

5 

_ 

X3 

•* 

r-l 

1-1 

CM 

bo 

c3 

bo 

CO 

co 

CO 

co 

a 

H 

C 

> 

J 

J3 

■ 

+j 

iH 

00 

iH 

o 

-t-> 
O 

CO 

ec 

H 

T-t 

•* 

E-t 

$ 

M 

o 

t- 

o 

Q> 

eo 

rH 

CO 

O) 

3 

a 

i-H 

CI 

Tf 

CM 

CM 

CM 

ti 

0 

CD 

CO 

CO 

> 

O 

(3 

< 

tu  " 

-I  CO 

CQ  « 

<  '*■ 

I-  CO 


*> 

It 

c 
• 

Ss 

CD 

^ 

eo   co 

E 

re 

"D 

o 

o 

en  oq 

't_ 

h- 

m 

T~ 

*" 

d  d 

V 

Q. 

X 

V 

5  s 

CO 

CO     CO 
CO    CM 

T3    •" 

5? 

a 

c 

*" 

■" 

11   "r" 

4) 

■     ^ 



co 

M 

t>-  o 

5  ■? 

re 

Ol 

m 

■^r 

CM    1- 

en 

H 

c 

T" 

T" 

T"  "r" 

c 

• 

T3 

"re 

CM 

00 

CM    CO 

— 

4* 

O) 

O 

ai 

CO    CO 

^ 

h 

c 

CO 

CM 

CM    CM 

■a    I 

1 

' 

> 

en 

O    "* 

E 

CM 

io  r^ 

— 

O 

o  o 

V 

re 

*> 

OC 

1- 

E 

4) 

E 

T3 

> 

*d 

r^ 

eo  co 

a 

E 

O) 

•- 

eo  ^J- 

Q. 

a> 

X 
0 

OC 

H- 

o 

i  > 

■o 

N 

00 

i-  en 

.E  S 

re 

o 

fs 

i-- 

CO    N- 

1- 

CQ 

O 

o 

o   O 

.E   en 

o>  ,_ 

V 

00    E 

>» 

*• 

en 

t-     CO 

a. 
< 

73 
O 
03 

O) 

c 
<> 

CO 

r^ 

CO    N. 

£ 

*> 

D) 

e 

o 

_ 

CM 

«- 

CO    CM 

re 

O) 

cc 

to 

co  co 

en 

c 

1- 

u 

> 

-1 

£ 

-M 

cr 

T— 

N.    O 

o 

o 

o> 

B 

r* 

^ 

*    >* 

1- 

V 

•    ^ 

•    re 

•  *> 

c 

■ 

o 

-t-" 

.~      CO 

o       7 

re  «t  re 

re      v 

re  «* 

^ 

a 

c 

o 

ro  7, 

O 

o 

-t- 

* 

.      V 

c 

0 

V      t. 

c 

c 

C    £ 

!  c 

o 

O  H 

167]  RATE  OF  REGENERATION— ZELENY  167 


BIBLIOGRAPHY 
Abel  M. 

1902.  Beitrage  zur  Kenntnis  der  Regenerationsvorgange  bei  den  limicolen 
Oligochaeten.    Z.  f.  wiss.  zool.,  63:1-74. 

Allen,  W.  E. 

191 1.    A  Study  of  the  Relation  of  Tissue  Differentiation  to  Rate  of  Growth 
during  Regeneration.    Biol  Bull.,  21 :  187-206. 
Barfurth,  D. 

1903.  Die  Erscheinungen  der  Regeneration  bei  Wirbeltierembryonen.  O. 
Hertwig's  Handbuch  der  Entwickelungslehre  der  Wirbeltiere. 

Bonnet,  C. 

1745.    Traite    d'insectologie.      Seconde    partie.      Observations    sur    quelques 
especes  de  vers  d'eau  douce,  qui,  coupe  par  morceaux  deviennent  autant 
d'animaux  complets.     Paris. 
Davenport,  C.  B. 

1899.    Experimental  Morphology,  Part  II,  New  York. 
Driesch,  Hans 

1897.  Studien  iiber  das  Regulationsvermogen  der  Organismen,  I.  Von  den 
regulativen  Wachstums-und  Differenzirungs-fahigkeiten  der  Tubularia. 
Arch.  f.  Entw.  Mech.,  5:389-418. 

Durbin,  Marion  L. 

1909.    An  Analysis  of  the  Rate  of  Regeneration  Throughout  the  Regener- 
ative Process.    J.  Exp.  Zool.,  7  :397-420. 
Ellis,  M.  M. 

1909.    The  Relation   of  the  Amount  of   Tail   Regenerated  to  the   Amount 
Removed  in  Tadpoles  of  Rana  clamitans.    J.  Exp.  Zool.,  7  :42i-456. 
Em  mel,  V.  E. 

1006.    The  Relation  of  Regeneration  to  the  Molting  Process  in  the  Lobster. 
Thirty-sixth  Annual  Report  of  the  Commissioners  of  Inland-Fisheries  of 
Rhode  Island.     Special  paper,  no.  27:257-313. 
Kam merer,  Paul 

1905.    Ueber    die   Abhangigkeit    des    Regenerationsvermogens    der   Amphib- 
ienlarven  von  Alter,  Entwicklungsstadium  und  spezifischer  Grosze.    Arch, 
f.  Entw.  Mech.,  19:148-180. 
King,  Helen  D. 

1898.  Regeneration  in  Asterias  vulgaris.    Arch.  f.  Entw.  Mech.,  7  :35i-363. 
Minot,  C.  S. 

1908.    Age,  Growth  and  Death.    New  York. 


168  ILLINOIS  BIOLOGICAL  MONOGRAPHS  [168 

Morgan,  T.  H. 

1902.  Further  Experiments  on  the  Regeneration  of  the  Tail  of  Fishes.  Arch. 
f.  Entw.  Mech.,  14:539-561. 

1906.  The  Physiology  of  Regeneration.    J.  Exp.  Zool.,  3  :457-50o. 
1909.    The  Dynamic  Factor  in  Regeneration.    Biol.  Bull.,  16:265-276. 

Morgulis,  S. 

1907.  Observations  and  Experiments  on  Regeneration  in  Lumbriculus.  J. 
Exp.  Zool,  4:549-574. 

1909a.  Regeneration  in  the  Brittle-Star  Ophiocoma  pumila,  with  Special  Ref- 
erence to  the  Influence  of  the  Nervous  System.  Proc.  Amer.  Acad,  of  Arts 
and  Sc,  44:655-659. 

1909b.  Contributions  to  the  Physiology  of  Regeneration.  I.  Experiments  on 
Podarke  obscura.    J.  Exp.  Zool.,  7:595-642. 

1909c.    Contributions  to  the  Physiology  of  Regeneration.    II.   Experiments  on 
Lumbriculus.    Arch.  f.  Entw.  Mech.,  28:396-439. 
Przibram,  Hans 

1906.  Aufzucht,  Farbwechsel  und  Regeneration  einer  agyptischen  Gottesan- 
beterin  (Sphodromantis  bioculata  Burm).  Arch.  f.  Entw.  Mech.,  22: 
149-192. 

Scott,  G.  G. 

1907.  Further  Notes  on  the  Regeneration  of  the  Fins  of  Fundulus  heterocli- 
tus.     Biol.  Bull.,  12:385-400. 

1909.    Regeneration  in  Fundulus  and  its  Relation  to  the  Size  of  the  Fish. 
Biol.  Bull.,  i7:343-353- 
Spallanzani,  Lazarq  Abbe 

1769.    An  Essay  on  Animal  Reproductions.    Translated  by  M.  Maty.    London. 
Stockard,  C.  R. 

1908.  Studies  of  Tissue  Growth,  I.  An  Experimental  Study  of  the  Rate  of 
Regeneration  in  Cassiopea  xamachana.  Carnegie  Institution  Publication 
No.  103:63-102. 

1909a.  Studies  of  Tissue  Growth,  II.  Functional  Activity,  Form  Regulation, 
Level  of  the  Cut,  and  Degree  of  Injury  as  Factors  in  Determining  the  Rate 
of  Regeneration.  The  Reaction  of  Regenerating  Tissue  in  the  Old  Body. 
J.  Exp.  Zool.,  6:433-471. 
1909b.  Studies  of  Tissue  Growth,  IV.  The  Influence  of  Regenerating  Tissue 
on  the  Animal  Body.  Arch.  f.  Entw.  Mech.,  29:15-32. 
Ubisch,  Leopold  v. 

1915.    Tiber  den  Einflusz  von  Gleichgewichtsstorungen  auf  die  Regenerations- 
geschwindigkeit.    Arch.  f.  Entw.  Mech.,  41 :237-25o. 
Vanlair,  C. 

1894.     Recherches  chronometriques  sur  la  regeneration  des  nerfs.     Archives 
de  physiologie  normale  et  pathologique.    5e  Serie.,  6:217-231. 
Zeleny,  C. 

1902.  A  Case  of  Compensatory  Regulation  in  the  Regeneration  of  Hydroides 
dianthus.    Arch.  f.  Entw.  Mech.,  13  :597-6o9. 

1903.  A  Study  of  the  Rate  of  Regeneration  of  the  Arms  in  the  Brittle-Star, 
Ophioglypha  lacertosa.     Biol.  Bull.,  6:12-17. 


169]  RATE  OF  REGENERATION— ZELENY  169 

1905a.    Compensatory  Regulation.     J.  Exp.  Zool.,  2:1-102. 
1905b.    The  Relation  of  the  Degree  of  Injury  to  the  Rate  of  Regeneration. 
J.  Exp.  Zool.,  2:347-369. 

1907,  The  Effect  of  Degree  of  Injury,  Successive  Injury  and  Functional 
Activity  upon  Regeneration  in  the  Scyphomedusan,  Cassiopea  xamachana. 
J.  Exp.  Zool.,  5:265-273. 

1908.  Some  Internal  Factors  Concerned  with  the  Regeneration  of  the  Chelae 
of  the  Gulf -Weed  Crab  (Portunus  sayi).  Carnegie  Institution  Publica- 
tion No.  103:103-138. 

1909a.  The  Effect  of  Successive  Removal  upon  the  Rate  of  Regeneration.  J. 
Exp.  Zool.,  7:477-512. 

1909b.  The  Relation  between  Degree  of  Injury  and  Rate  of  Regeneration — 
Additional  Observations  and  General  Discussion.    J.  Exp.  Zool.,  7  :5i3-562. 

1909c.  Some  Experiments  on  the  Effect  of  Age  upon  the  Rate  of  Regener- 
ation.   J.  Exp.  Zool.,  7:563-593- 

1912.    The  Quantitative  Study  of  the  Internal  Factors  Controlling  Regenera- 
tion.    Proc.  Seventh  Intern.  Zool.  Congress  1907:491-494. 
Zuelzer,  M. 

1907.  tJber  den  Einflusz  der  Regeneration  auf  die  Wachstumsgeschwindig- 
keit  von  Asellus  aquaticus.    Arch.  f.  Entw.  Mech.»  25  :36i-397. 


UNIVERSITY  OF  ILLINOIS-URBAN  A 

S70.SILL  C004 

ILLINOIS  BIOLOGICAL  MONOGRAPHS  URBANA 

31916-17 


3  01 


017753408 


<CM$£iS)ic; 


&&m 


3L'ir>J3i.v^-jOiM 


,"''''•'---♦ fpp > '  •    }   ' v '  • '   •*        ' .  ■  ' . r 


£j,m&a,££ 


i^^^^j^^'^fHH^l^^^^^^^^^^^^ 


